Exhibit 8.1



Subsidiaries of Ecopetrol S.A.



The following table sets forth our subsidiaries,
their respective countries of incorporation, our percentage ownership in each (both directly and indirectly through other subsidiaries)
and our voting percentage in each at March 31, 2012.



|COMPANY                                                 |  | COUNTRY OF
        INCORPORATION |  | OWNERSHIP % |  | VOTING % | 
|------------------------------------------------------- |  | -------------------------------- |  | ----------- |  | -------- | 
|Andean Chemicals Ltd.                                   |  | Bermuda                          |  | 100         |  | 100      | 
|Bioenergy S.A.**                                        |  | Colombia                         |  | 91.43       |  | 91.43    | 
|Bioenergy Zona Franca S.A.S.**                          |  | Colombia                         |  | 91.43       |  | 91.43    | 
|Black Gold Re                                           |  | Bermuda                          |  | 100         |  | 100      | 
|Colombia Pipelines Limited**                            |  | United Kingdom                   |  | 51          |  | 51       | 
|COMAI - Compounding and Masterbatching Industry Ltda.** |  | Colombia                         |  | 100         |  | 100      | 
|Ecopetrol America Inc.*                                 |  | United States                    |  | 100         |  | 100      | 
|Ecopetrol Capital AG                                    |  | Switzerland                      |  | 100         |  | 100      | 
|Ecopetrol del Perú S.A.*                                |  | Perú                             |  | 100         |  | 100      | 
|Ecopetrol Global Capital S.L.U.                         |  | Spain                            |  | 100         |  | 100      | 
|Ecopetrol Global Energy S.L.U.                          |  | Spain                            |  | 100         |  | 100      | 
|Ecopetrol Oleo e Gas do Brasil Ltda*                    |  | Brazil                           |  | 100         |  | 100      | 
|Ecopetrol Pipelines International Ltd.**                |  | Bermuda                          |  | 100         |  | 100      | 
|Ecopetrol Transportation Company Limited                |  | Cayman Islands                   |  | 100         |  | 100      | 
|Ecopetrol Transportation Investments Ltd.*              |  | Bermuda                          |  | 100         |  | 100      | 
|Equion Energy Ltda                                      |  | United Kingdom                   |  | 51          |  | 51       | 
|Hocol Petroleum Limited**                               |  | Bermuda                          |  | 100         |  | 100      | 
|Hocol Limited**                                         |  | Bermuda                          |  | 100         |  | 100      | 
|Hocol S.A.**                                            |  | Cayman Islands                   |  | 100         |  | 100      | 
|Homcol Cayman Inc.**                                    |  | Cayman Islands                   |  | 100         |  | 100      | 
|ODL Finance S.A.                                        |  | Panama                           |  | 65          |  | 65       | 
|Offshore International Group Inc. – OIG(1)              |  | United States                    |  | 50          |  | 50       | 
|Oleoducto Bicentenario de Colombia S.A.S.*              |  | Colombia                         |  | 55.97       |  | 55.97    | 
|Oleoducto Central S.A.*                                 |  | Colombia                         |  | 72,65       |  | 72,65    | 
|Oleoducto de Colombia S.A.*                             |  | Colombia                         |  | 73          |  | 73       | 
|Oleoducto de los Llanos Orientales S.A. **              |  | Panama                           |  | 65          |  | 65       | 
|Propilco S.A.*                                          |  | Colombia                         |  | 100         |  | 100      | 
|Refinería de Cartagena S.A.*                            |  | Colombia                         |  | 100         |  | 100      | 
|Santiago Oil Co. **                                     |  | Cayman Islands                   |  | 51          |  | 51       | 
|Santiago Pipelines Co.**                                |  | Cayman Islands                   |  | 51          |  | 51       | 
|Savia Perú S.A.**(1)                                    |  | Peru                             |  | 50          |  | 50       | 



---



*   Direct and indirect participation.

** Solely indirect participation through other Subsidiaries
or Affiliates.  OIG is the parent company of Savia Perú S.A., and Ecopetrol Transportation Company is the parent
company of Ecopetrol Pipelines Ltd.

(1) Affiliate.