The commissioner of the Independent Commission Against Corruption (ICAC), Megan Latham, says it is unlikely a corrupt conduct finding will be made against Senator Arthur Sinodinos.

Senator Sinodinos is listed as a witness in an ICAC inquiry into Australian Water Holdings (AWH) and has stood aside as assistant treasurer while the probe continues.

The company is accused of corruptly obtaining money from the New South Wales state-owned Sydney Water and using the money for executive salaries and donations to the Liberal Party around the time Senator Sinodinos was on the AWH board.

Corrupt conduct allegations were not made against him at the start of the inquiry, but some witnesses have stated that he was warned that the directors of AWH were dishonest.

There have also been various allegations about him being questioned over the company's expenses.

On Wednesday, when addressing a lawyer at the hearing about various matters, Ms Latham said she found it difficult to believe a corrupt conduct finding would be made against Senator Sinodinos.

"Whether a corrupt conduct finding could ever be made against Mr Sinodinos ... I have myself some difficulty in seeing how that could occur," the commissioner said.

Earlier, the inquiry heard Senator Sinodinos stood to make millions from a deal involving AWH.

He has stood aside from his frontbench post while ICAC investigates the dealings of the company.

Senator Sinodinos maintains he has done nothing wrong and Prime Minister Tony Abbott predicts he will return to the frontbench "soon".

Senator Sinodinos is expected to face the inquiry next week, while former NSW premier Kristina Keneally will give evidence today.

ICAC has heard she was premier when former NSW Labor ministers Joe Tripodi and Tony Kelly allegedly "doctored" a cabinet minute about a proposal between AWH and Sydney Water.

The inquiry heard the minute was in favour of AWH because the ministers' Labor colleague, Eddie Obeid, had a secret stake in the company.