Abstract: A commercial gas oven has as its only source of heat for heating and for steam generating an extended mesh-type burner and a sealed combustion chamber. The oven works in five cooking modes reaching steam saturation below 100.degree. C. and a high humidity up to 250.degree. C., combining air convection from a central turbine and the steam which is generated into the oven. At least one steam generator duct conveys the combustion fumes around a central turbine on whose surface falls the water sprayed from a sprayer linked to the turbine. The fumes are recovered to contribute to heating the cooking chamber by means of a takeup box.