Company: ALCE
Filing Date: 2025-11-17
Form Type: NT 10-Q
Source: 0001213900-25-111427
Chunk: 0

Company: Alternus Clean Energy, Inc.
Filing Date: 2025-11-17
Form: NT 10-Q
Chunk 0
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<div align='center'>UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, DC 20549

FORM 12b-25

NOTIFICATION OF LATE FILING

(Check one): ☐ Form 10-K ☐ Form
20-F ☐ Form 11-K ☒ Form 10-Q ☐ Form N-SAR ☐ Form N-CSR</div>

For Period Ended: 9/30/2025

| ☐ | Transition Report on Form 10-K |

| ☐ | Transition Report on Form 20-F |

| ☐ | Transition Report on Form 11-K |

| ☐ | Transition Report on Form 10-Q |

| ☐ | Transition Report on Form N-SAR |

For the Transition Period Ended: n/a

Nothing in this form shall be construed to imply
that the Commission has verified any information contained herein.

If the notification relates to a portion of the
filing checked above, identify the item(s) to which the notification relates:

<div align='center'>PART I -- REGISTRANT INFORMATION

ALTERNUS CLEAN ENERGY, INC.

Full Name of Registrant

N/A

Former Name if Applicable

17 State Street, Suite 4000

Address of Principal Executive Office (Street and
Number)

New York City, NY 10004

City, State and Zip Code

PART II -- RULES 12b-25(b) AND (c)</div>

If the subject report could not be filed without
unreasonable effort or expense and the registrant seeks relief pursuant to Rule 12b-25(b), the following should be completed. (Check box
if appropriate)

| ☒ | -a | The reasons described in reasonable detail in Part III of this form could not be eliminated without unreasonable effort or expense;                                                                                                                                                                                                                                                                                         |
|   | -b | The subject annual report, semi-annual report, transition report on Form 10-K, Form 20-F, Form 11-K, Form N-SAR or Form N-CSR, or portion thereof, will be filed on or before the fifteenth calendar day following the prescribed due date; or the subject quarterly report or transition report on Form 10-Q, or portion thereof, will be filed on or before the fifth calendar day following the prescribed due date; and |
|   | -c | The accountant's statement or other exhibit required by Rule 12b-25(c) has been attached if applicable.                                                                                                                                                                                                                                                                                                                     |

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