Bankrupt Kathy Jackson allegedly bought interior furnishings, boozy meals and PlayStation games with her Health Services Union credit cards.
The union also says she paid for holidays and divorce proceedings with money from the cards.
Ms Jackson, who declared bankruptcy late last month, is being sued by the HSU for upwards of $2.5 million.
She hasn’t appeared in the Federal Court for the civil trial, in which the HSU alleges Ms Jackson misappropriated about $660,000 in union funds.
Barrister Mark Irving, acting for the HSU, on Wednesday scrutinised about $340,000 worth of Ms Jackson’s work credit card spending, saying items such as staff gifts or a coffee with colleagues weren’t reasonably union-related.
He outlined alleged purchases of more than $2000 for interior furnishings, a boozy group dinner at the Press Club restaurant in Melbourne totalling about $2200, videos and PlayStation games.
Other food and liquor purchases “clearly show” Ms Jackson purchasing family groceries, Mr Irving alleged.
Ms Jackson, the former HSU national secretary, set up the National Health Development Account in 2003.
The union says Ms Jackson used the account to hold union funds entirely under her control.
Some money paid for holidays, and withdrawals on the account also appeared to match deposits into Ms Jackson’s personal and mortgage accounts, Mr Irving told the court.
He said some or all of about $100,000 withdrawn from the account was spent on Ms Jackson’s divorce proceedings, court documents show.
The court heard Ms Jackson was earning $170,000 a year as national secretary and received a $63,000 honorarium from the union’s Victorian branch, which the HSU wants back.
Mr Irving told the court Ms Jackson withdrew “vast wads” of union cash.
He alleged she cashed cheques, gave branch committee of management members $100 each at meetings and pocketed the rest, despite saying the money was returned into a union kitty.
Ms Jackson wrote to the court to say she could not afford to be represented at the trial and that the matter was now a claim against her estate.
She has denied any wrongdoing.
The trial is expected to end on Thursday.