It is estimated that Caltex controls 16.8 percent of the retail fuel market. Currently, Caltex is the exclusive supplier of petrol and diesel to Woolworths, with annual sales volumes of around 3.5 billion litres each year.
The company says it made a conditional and confidential proposal to Woolworths to acquire its petrol business.
Woolworths' asking price to sell its fuel business is expected to be around $1.6 billion, and BP may also be one of Caltex’s rival bidders.
Caltex posted a net profit of $318.7 million at 30 June 2016.