Abstract: A fuel heater for heating fuel flowing in the fuel system of an internal combustion engine has an annular heating chamber in which is mounted a heating element formed from a material having a non-linear positive temperature coefficient of resistance. The element defines an upwardly extending flow passage and the heater includes a cup-shaped support member having a central aperture and an annular baffle plate 25 which forms the upper wall of the chamber. Cold fuel is led through gaps at the outer edge of the baffle plate and flows along the base wall of the chamber and then upwardly through the flow passage of the element. The heated fuel flows from the chamber through a space defined between an upwardly extending lid of the support member and a depending tubular element of the baffle plate.