Algy Cluff is stepping down as the chief executive of the oil company he set up in 2012 in order to spend time on other interests, including the launch of a new charity.
Cluff Natural Resources has appointed finance director Graham Swindells as its new boss, and Cluff will remain chairman of the firm.
Cluff, a UK oil veteran who pioneered North Sea exploration in the 1970s, said: "I have committed myself to our company since its inception, but I am now at the stage where I wish to step back from my full-time role."
He added that either Swindells or chief operating officer Andrew Nunn would be a worthy successor, but the appointment of the former will allow Nunn to "concentrate exclusively" on the firm's North Sea objectives.
Swindells said he was excited to build on the foundations laid by Cluff.
"Our existing oil and gas assets are highly prospective and with additional licence awards anticipated when the UK's 30th Licencing Round is announced in Q2 2018, we are well positioned to develop a diversified portfolio of exploration assets from which to create value for our shareholders," he said.
Shares in Cluff Natural Resources, which is listed on London's junior market, were down more than five per cent at 2.23p at the time of writing.