British power producer Drax said chief executive Dorothy Thompson will step down after 12 years in the role.
The company's current finance chief Will Gardiner will succeed Dorothy Thompson who will step down from the post and leave the group at the end of 2017.
Shares of the company, which owns the UK's largest power station, fell 1.5 percent in early trading.
Drax is speeding up plans to convert its units to gas.
Under pressure from government plans to close all coal plants by 2025, Drax has increasingly turned to burning compressed wood pellets, or biomass.
The company will begin the process of appointing a new chief financial officer and will also review the option of making an appointment on an interim basis, it said on Thursday.