Goal of the thesis is to develop a meter for the measurement of the instantaneous flow rate at high pressures (the experimental tests oscillate between a minimum pressure of 600 bar and a maximum of 1800 bar). The research and studies took place with the collaboration of the Rabotti company and all experimental tests were conducted in the laboratory of the Energy Department of the Polytechnic. The meter is based on the detection of pressure, carried out by means of two high-performance piezoresistive transducers, in two points placed at an appropriate distance along a sufficiently rigid duct with a constant diameter where diesel, petrol or mineral oil flows inside.