A thermostat for gas-powered cooking appliances includes a body having an inlet conduit and an outlet conduit that respectively receive and supply a gas flow, and a chamber in fluid communication both with the inlet conduit, and also with the outlet conduit either directly, through a main opening formed at one end thereof, or indirectly, through a secondary conduit formed in the body of the thermostat, which reaches the outlet conduit bypassing the main opening. A valve that adjusts gas flow rate is coaxially fitted in the chamber and has a position that is controlled by an expandable member of a thermostatic bulb of the thermostat. The valve is axially deformable beyond a predefined load threshold and compensates for dilations of the expandable member under a normal operating condition, absorbing axial forces exerted by the thermostat knob when rotated to switch off a burner driven by the thermostat.