A heating pad with electric heating and heat storage means and a phase change material (27, 28) for maintaining the temperature comprises an electronic system (21) for controlling electric resistors (25) for heating the phase change material. The electronic system comprises in turn first means (44) for measuring the temperature of the phase change material, second means (43) for measuring the energy Qd supplied over time to the heating resistors, calculation means (47) for calculating the quantity of energy Q necessary for heating the phase change material from the initial temperature measured by the first means (44) to a desired final temperature, and comparison means (48) which compare the quantity of energy Q calculated and the energy Qd supplied to the resistors in order to define an end condition of heating of the phase change material.
