The present invention relates to a micromechanical power generator which can be applied in a wide range of applications and, in particular, in the field of energy harvesting. The power generator comprises of a micro heat engine arranged between two reservoirs having different temperatures, the said micro heat engine being operable to move a transducing member between a first position where it is in thermal contact with the first reservoir and a second position where it is in thermal contact with the second reservoir, thereby transforming the spatial temperature difference between the two reservoirs into a temporal temperature variation. According to the present invention, the said transducer member is thermally coupled to a pyroelectric member for transforming the said temporal temperature variation into electric power.