A former senior WA Government media advisor charged with allegedly indecently assaulting a colleague at a staff Christmas party in December is set to face trial after pleading not guilty.

Key points: Stephen Kaless resigned after a woman complained about his behaviour

Stephen Kaless resigned after a woman complained about his behaviour He was then charged with indecent assault following a police investigation

He was then charged with indecent assault following a police investigation A two-day trial will be held after Mr Kaless pleaded not guilty to the charge

Stephen Kaless resigned as one of Treasurer Ben Wyatt's most senior staff members after a complaint about his behaviour at the party prompted him to be suspended indefinitely from his position.

Police allege he indecently assaulted a woman in her 20s, who was known to him, inside the bar area of a Perth hotel on December 13.

Mr Kaless walked into court on Wednesday morning holding hands with his wife.

Mr Kaless arrived at court with his lawyer (left) and his wife (right). ( ABC News: Hugh Sando )

His lawyer, Carolyn Smiddy-Brown, told the court that one hour of CCTV footage would be used as evidence.

She said the prosecution had four witnesses and there were two possible witnesses for the defence.

"Mr Kaless is looking forward to his day in court," she said outside court.

Mr Kaless worked as a senior media adviser to Mark McGowan in opposition. ( ABC News )

Mr Kaless had been Mr Wyatt's key media adviser since Labor's 2017 election victory.

Prior to that he worked for four years as the chief of staff of the Channel 7 Perth newsroom.

He also previously worked as an adviser to Mr McGowan during his time as opposition leader and had been a media officer for UnionsWA.

The trial has been set down for two days, with a trial allocation hearing to be held next week to determine a date.