Exhibit 8.1

List of subsidiary companies

At
31 December 2015

The principal operating subsidiary companies of the Rio Tinto Group are listed in Note 33 to the 2015 Financial
statements. The principal intermediate holding companies and group finance companies are as follows:



|                                             |  |                                             |  |                                                         |     |                          |     |  |                |  |     | 
|-------------------------------------------- |  | ------------------------------------------- |  | ------------------------------------------------------- | --- | ------------------------ | --- |  | -------------- |  | --- | 
|Company and country of
incorporation         |  | Principal activities                        |  | Class of
shares held                                    |     | Proportionof classheld
% |     |  | Groupinterest% | 
|                                             |  |                                             |  |                                                        
|Australia                                    |  |                                             |  |                                                         |     |                          |     |  |                |  |     | 
|Australian Coal Holdings Pty. Limited        |  | Holding company                             |  | AUD A shares                                            |     |                          | 100 |  |                |  | 100 | 
|Hamersley Holdings Limited                   |  | Holding company                             |  | AUD Ordinary shares                                     |     |                          | 100 |  |                |  | 100 | 
|North IOC Holdings Pty Ltd                   |  | Holding company                             |  | AUD Ordinary shares                                     |     |                          | 100 |  |                |  | 100 | 
|North Limited                                |  | Holding company                             |  | AUD Ordinary shares                                     |     |                          | 100 |  |                |  | 100 | 
|Pacific Aluminium Pty. Limited               |  | Holding company                             |  | AUD Ordinary shares                                     |     |                          | 100 |  |                |  | 100 | 
|Peko-Wallsend Pty Ltd                        |  | Holding company                             |  | AUD Ordinary shares                                     |     |                          | 100 |  |                |  | 100 | 
|Rio Tinto Finance Limited                    |  | Finance company                             |  | AUD Ordinary shares                                     |     |                          | 100 |  |                |  | 100 | 
|Rio Tinto Finance (USA) Limited              |  | Finance company                             |  | AUD Ordinary shares                                     |     |                          | 100 |  |                |  | 100 | 
|Rio Tinto Investments One Pty Limited        |  | Holding company                             |  | AUD Ordinary shares                                     |     |                          | 100 |  |                |  | 100 | 
|Rio Tinto Investments Two Pty Limited        |  | Holding company                             |  | AUD Ordinary shares                                     |     |                          | 100 |  |                |  | 100 | 
|Robe River Limited                           |  | Holding company                             |  | AUD Ordinary shares                                     |     |                          | 100 |  |                |  | 100 | 
|                                             |  |                                             |  |                                                        
|Bermuda                                      |  |                                             |  |                                                         |     |                          |     |  |                |  |     | 
|North IOC (Bermuda) Holdings Limited         |  | Holding company                             |  | US$1.00 Ordinary shares                                 |     |                          | 100 |  |                |  | 100 | 
|North IOC (Bermuda) Limited                  |  | Holding company                             |  | US$1.00 Ordinary (US$1.00) shares                       |     |                          | 100 |  |                |  | 100 | 
|                                             |  |                                             |  | US$143.641269 Class A Ordinary shares
(US$143.64126903) |     |                          | 100 |  |                |  | 100 | 
|                                             |  | US$100,000.00 Preferred shares
(US$100,000) |  |                                                         | 100 |                          |     |  | 100            | 
|QIT Madagascar Minerals Ltd.                 |  | Holding company                             |  | US$1.00 Ordinary shares                                 |     |                          | 100 |  |                |  | 100 | 
|                                             |  |                                             |  |                                                        
|Canada                                       |  |                                             |  |                                                         |     |                          |     |  |                |  |     | 
|46117 Yukon Inc.                             |  | Holding company                             |  | CAD Common shares                                       |     |                          | 100 |  |                |  | 100 | 
|                                             |  |                                             |  | CAD Preferred shares                                    |     |                          | 100 |  |                |  | 100 | 
|535630 Yukon Inc                             |  | Holding company                             |  | CAD Common shares                                       |     |                          | 100 |  |                |  | 100 | 
|                                             |  |                                             |  | CAD Preferred shares                                    |     |                          | 100 |  |                |  | 100 | 
|7999674 Canada Inc.                          |  | Holding company                             |  | CAD Common shares                                       |     |                          | 100 |  |                |  | 100 | 
|Rio Tinto Canada Inc                         |  | Holding company                             |  | CAD Class B shares                                      |     |                          | 100 |  |                |  | 100 | 
|                                             |  |                                             |  | CAD Class C shares                                      |     |                          | 100 |  |                |  | 100 | 
|                                             |  |                                             |  | CAD Class D shares                                      |     |                          | 100 |  |                |  | 100 | 
|                                             |  |                                             |  | CAD Class J shares                                      |     |                          | 100 |  |                |  | 100 | 
|Rio Tinto Finance Canada Inc.                |  | Finance company                             |  | CAD Ordinary shares                                     |     |                          | 100 |  |                |  | 100 | 
|                                             |  |                                             |  |                                                        
|Namibia                                      |  |                                             |  |                                                         |     |                          |     |  |                |  |     | 
|Skeleton Coast Diamonds Limited              |  | Holding company                             |  | NAD 2.00 Ordinary shares                                |     |                          | 100 |  |                |  | 100 | 
|                                             |  |                                             |  |                                                        
|Netherlands                                  |  |                                             |  |                                                         |     |                          |     |  |                |  |     | 
|Oyu Tolgoi Netherlands BV                    |  | Holding company                             |  | 100.00 Ordinary shares                                 |     |                          | 100 |  |                |  | 51  | 
|Rio Tinto Eastern Investments B.V.           |  | Holding company                             |  | 453.78 Ordinary shares                                 |     |                          | 100 |  |                |  | 100 | 
|Turquoise Hill Netherlands Cooperatif UA     |  | Holding company                             |  | US$ COOP share shares                                   |     |                          | 100 |  |                |  | 51  | 
|                                             |  |                                             |  |                                                        
|South Africa                                 |  |                                             |  |                                                         |     |                          |     |  |                |  |     | 
|Richards Bay Mining Holdings (Proprietary)   |  |                                             |  |                                                         |     |                          |     |  |                |  |     | 
|Limited                                      |  | Holding company                             |  | ZAR1.00 A Ordinary shares                               |     |                          | 100 |  |                |  | 100 | 
|                                             |  |                                             |  | ZAR1.00 B Ordinary shares                               |     |                          | 100 |  |                |  | 100 | 
|Richards Bay Titanium Holdings (Pty) Limited |  | Holding company                             |  | ZAR 0.01 B Ordinary shares                              |     |                          | 100 |  |                |  | 100 | 
|                                             |  |                                             |  | ZAR0.01 B Preference shares                             |     |                          | 100 |  |                |  | 100 | 
|                                             |  |                                             |  | ZAR0.01 BHP Billiton Preference shares                  |     |                          |     |  |                |  |     | 
|United Kingdom                               |  |                                             |  |                                                         |     |                          |     |  |                |  |     | 
|Rio Tinto European Holdings Limited          |  | Holding company                             |  | £1.00 Ordinary shares                                   |     |                          | 100 |  |                |  | 100 | 
|Rio Tinto Finance plc                        |  | Finance company                             |  | £1.00 Ordinary shares                                   |     |                          | 100 |  |                |  | 100 | 
|                                             |  |                                             |  | US$ 1.00 Ordinary shares                                |     |                          | 100 |  |                |  | 100 | 
|Rio Tinto International Holdings Limited     |  | Holding company                             |  | £1.00 Ordinary shares                                   |     |                          | 100 |  |                |  | 100 | 
|Rio Tinto Investments Limited                |  | Holding company                             |  | £1.00 Ordinary shares                                   |     |                          | 100 |  |                |  | 100 | 
|Rio Tinto Namibian Holdings Limited          |  | Holding company                             |  | £1.00 Ordinary shares                                   |     |                          | 100 |  |                |  | 100 | 
|Rio Tinto Overseas Holdings Limited          |  | Holding company                             |  | £1.00 Ordinary shares                                   |     |                          | 100 |  |                |  | 100 | 
|                                             |  |                                             |  | US1.00 Ordinary shares                                  |     |                          | 100 |  |                |  | 100 | 
|Rio Tinto Simfer UK Limited                  |  | Holding company                             |  | US$ 1.00 Ordinary shares                                |     |                          | 100 |  |                |  | 100 | 
|Rio Tinto Western Holdings Limited           |  | Holding company                             |  | £1.00 Ordinary shares                                   |     |                          | 100 |  |                |  | 100 | 
|                                             |  |                                             |  | US$ 1.00 Ordinary shares                                |     |                          | 100 |  |                |  | 100 | 
|United States of America                     |  |                                             |  |                                                         |     |                          |     |  |                |  |     | 
|Rio Tinto America Holdings Inc.              |  | Holding company                             |  | US$0.01 Class A Common shares                           |     |                          | 100 |  |                |  | 100 | 
|                                             |  |                                             |  | US$100.00 Series A Preferred Stock
shares               |     |                          | 100 |  |                |  | 100 | 
|Rio Tinto America Inc.                       |  | Holding company                             |  | US$100.00 Common shares                                 |     |                          | 100 |  |                |  | 100 | 
|Rio Tinto Minerals Inc.                      |  | Holding company                             |  | US$ 0.01 Common shares                                  |     |                          | 100 |  |                |  | 100 |