Among the first witnesses will be County Fire Authority chief officer Russell Rees, Department of Sustainability and Environment fire and emergency management director Ewan Waller, Emergency Services Commissioner Bruce Esplin, and Victoria Police deputy commissioner Kieran Walshe.

Watch a webcast of the commission hearings here from 9.30am

Commission chairman Bernard Teague has said the main focus of the first eight-week block of hearings would be what happened on Black Saturday, warnings and aspects of the "Stay or Go" policy.

The commission will look at individual fires, including their timing and intensity, and the effect on them of wind and the south-westerly change that day.

The fires, on February 7, killed 173 people, destroyed 2500 homes and are said to be Australia's worst peacetime disaster.

"We will concentrate on how to limit the devastation of any future intense bushfires and save lives," Mr Teague said.

The commission has granted any parties likely to be scrutinised the right to have a lawyer appear on their behalf.

Among them are the Federal Government, the Municipal Association of Victoria (representing all local councils) and the State Government, including the Country Fire Authority, the Department of Sustainability and Environment, the Emergency Services Telecommunications Authority, Victoria Police, the Department of Premier and Cabinet, and the Department of Justice.

Conditional leave to appear gives a party permission to be legally represented regarding specific subjects.

It has been granted to 13 organisations, including the United Firefighters Union, the Australian Workers Union, the Insurance Council of Australia, Telstra, Powercorp and the Police Association.

The hearings will be streamed on the internet and will be available for live viewing in many libraries. The State Library of Victoria will stream the first four days in a room that can seat 300 people.

The commission held 26 community consultations in fire-affected areas and has received more than 180 written submissions.

It is due to deliver an interim report on August 17 and a final report on July 31, 2010.