The House of Commons authorities are expected to publish details of MPs' travel expense claims on Wednesday.
Norman Baker wants a detailed breakdown of travel costs
They have to publish by then after the Commons lost an Information Tribunal case brought by Liberal Democrat MP Norman Baker.
Mr Baker has fought a two-year battle for a detailed breakdown, rather than the current combined figure.
The figures are expected to show plane fares, train tickets and car costs.
Mr Baker said he believed that the public was entitled to know how its money is being spent.
He said publishing detailed figures would act as a downward pressure on claims and would make clear the effect on the environment through their air travel.
Figures released in October 2006 revealed that MPs had claimed almost £86.8m in expenses and allowances during the previous year, an increase of nearly £6m on the previous year.
The Commons, which lost two appeals, had argued that revealing further details would breach data protection principles.