A cooking oven has a cooking cavity and a steam generating system. The steam generation system includes a water reservoir received and support in a reservoir-receiving space of a reservoir rack inside the cooking cavity. Thermal energy is provided to the water reservoir by a heater inside the cooking cavity. The heater can include thermal block made of a thermally conductive material in thermal communication with a heating element. The heater can be positioned such that it intimately contacts the water reservoir to deliver thermal energy thereto to convert water contained therein to steam, which can be used to cook a food item inside the cooking cavity.