The man in charge of the University of Sussex is to step down after nine years in charge.

Vice-chancellor Alasdair Smith announced yesterday he would leave the university in Falmer, Brighton, in August 2007, a year earlier than expected.

He said the move was intended to allow his successor a reasonable amount of time in office to prepare for the national Research Assessment Exercise of the university in 2008.

Prof Smith, 57, said: "It has been a very significant decision for me and will bring about a big change in my life but I have decided this is the best timing for the university."

Prof Smith started a second five-year term as vice-chancellor in 2003 and was due to step down in 2008. He said he was not planning to go into retirement yet but was unlikely to take up another full-time post.

His time in office at Sussex has seen one of the most successful periods in its history.

The university's popularity with undergraduates has grown steadily and it reached the top 20 in national league tables. Research work at Sussex has seen it ranked in the top 100 internationally. The university population has risen from 9,200 to 10,600.

Prof Smith said he was proud to have been involved in the founding of the medical school, a partnership between the University of Brighton and the University of Sussex.

He said yesterday: "Institutions need new leaders and new ideas from time to time."

Sam Younger, chairman of the university's governing body, said he applauded Prof Smith's thoughtful and considered approach.

He said: "Alasdair's leadership over the last eight years has moved Sussex forward significantly and he has given the university, and his successor, a solid platform for meeting the challenges ahead."

Prof Smith first joined Sussex in 1981 as a professor of economics and later became dean of the school of European studies.

He has not been universally popular throughout his time in charge. A controversial decision earlier this year to close the university's chemistry department, later reversed, was followed by a hard-line stance on lecturers' demands for wage increases. He docked pay from those who refused to mark exam papers.

Prof Smith also supported the introduction of fees as a way of funding higher education.

He said he had not yet made his plans for the future but would continue living at his home in Lewes and probably take a series of part-time positions.

His announcement follows the news this week that the University of Chichester has appointed a new vice-chancellor. Dr Robin Baker, currently a pro-vice-chancellor at the University of Kent will succeed Philip Robinson when he retires next year.