Mozilla has announced that chief executive Mitchell Baker is stepping down in favour of chief operating officer John Lilly.

Baker will remain as chairman of the open source non-profit organisation, but Lilly will take over effective operations immediately.

The timing of the announcement, in the middle of the Consumer Electronics Show in Las Vegas, will surprise many but appears to have been well planned.

"Sometimes in life, you find an opportunity to make a difference in something you care about, and it feels that the last few years have really just been practice, giving you the background, skills and ability to really help," said Lilly in his blog.

"And in a very few circumstances the opportunity you get to make a difference is one that has a very large, even global impact. My new role as chief executive of Mozilla Corporation feels like one of those times."

Lilly has good credentials. He has been a director at the Open Source Applications Foundation for the past seven years and has concentrated on building up smaller companies.

Mitch Kapor, board member and former chairman of the Mozilla Foundation, said: "I have worked with Mitchell and John for a number of years, and I strongly support these moves at Mozilla.

"It should allow the organisation to do more things than ever before, and to do them well."

The decision will be good news for those concerned that Mozilla might go public and cash-in on its success. Annual revenues have grown to over $50m and the organisation is expanding to further develop its software.

But Lilly has previously signalled his opposition to such a move. "There is no presumption that for-profit or, more properly, non-tax-exempt, entities are bad and non-profits are good," he said in a blog posting earlier this year.

"That is a ridiculous and naive position to take. I have been part of many for-profit companies and there are many who do incredibly important things for their shareholders and the world.

"But the reason that we are non-tax-exempt in the Mozilla Corporation is so that we can properly pay taxes, not to maximise profits."