Aldermen Ed Burke and George Cardenas introduced a proposal banning the products at Wednesday's city council meeting.
Mayor Emanuel says he'll study the proposal and pointed to improvements in the environment since he took office.
"We've been debating for 10 years, whether we should close two coal-fired power plants, they're now closed. We've been debating for years whether we should have citywide recycling in every neighborhood, not just in select neighborhoods, we do now," said Mayor Emanuel.
More than 100 cities around the country have put polystyrene bans in place.
There would be exemptions for food packaged outside of Chicago but sold here.