UNIONS say more than 150 people rallied outside Esso's Australian headquarters in Southbank, Melbourne, on Thursday.
The Australian Manufacturing Workers' Union, the Australian Workers' Union and the Electrical Trades Union organised the rally, protesting reduced wages and conditions for UGL maintenance workers at Esso's Longford and offshore sites, the use of what they say are loopholes in the Fair Work Act, Australian gas being sent overseas and high domestic gas and electricity prices.
Local protesters were bussed to Melbourne for the event.
Electrical Trades Union spokesperson Rory McCourt said the rally included mums, dads, children and union members, describing the mood as "defiant".
"It was a fantastic turnout," he said, adding the workers telling their personal stories was "particularly powerful".
Mr McCourt said company moves to reduce wages and conditions were taking a toll on families, but added the union campaign was getting "bigger and bigger", as people began to realise the ramifications of corporations creating "shelf companies", which used unrelated workers to sign up to what he said were unfair agreements.
"We're calling for the Fair Work Act to be overhauled," he said.
"If there was any justification for these pay cuts, it would be different.
"But company profits are through the roof; gas prices are through the roof."
Mr McCourt said CEOs and politicians were not taking 30 per cent pay cuts or working in dangerous offshore and onshore environments.
"It's double standards," he said.
"We know this industry is so dangerous."
Mr McCourt said some Esso workers stepped out of their offices to monitor Thursday's rally.
He also accused UGL and Esso of "hiding behind" the Australian Mines and Metals Association, which has been publicly commenting about the dispute.
Esso Australia chairman Richard Owen is also the AMMA board president.
Union mascots Scabby the Rat (the subject of an interim court order banning him from the Longford protest site) and Greedy the Fat Cat were inflated for the rally, also taking rides in boats on the Yarra River.