Abstract: A steam cleaning machine comprises a steam generator system including a tank for fuel, such as propane, a detergent tank, and connections to sources of air under pressure and water. A hand-held steam generator unit includes a central combustion chamber spaced inwardly of a surrounding jacket. A first conduit extends to the rear of the combustion chamber, carrying a combustible gas-air mixture. A water conduit extends to the rear of the jacket. The chamber has a spark plug extending into it, through the jacket, and the forward end of the combustion chamber has an axial exhaust pipe, surrounded by a steam discharge pipe connected to the outlet of the jacket. Downstream of the combustion chamber outlet pipe is a detergent inlet connected by a conduit to the detergent tank.