More than a hundred people attended a public meeting organised by a campaign group against a planned incinerator. Nottinghamshire County Council said several sites are being considered, including one on the Crown Farm Industrial Estate at Forest Town.
Protestors have formed Mansfield Against Incineration (MAIN) to fight the plans.
Most local councillors and county councillors are opposed, according to a MAIN spokesperson.
The protesters claim the development will cause pollution and damage the health of local residents.
Organiser Paul Frost said: "The next step is to move the campaign forward to get the publicity out, to make sure everyone in Mansfield knows what's going on and to make sure their voices are heard.
"The leader of the council David Kirkham and the environmental head Stella Smedley need to know the level of opposition we've got in Mansfield to these proposals."