Paper presents the characteristics of two hydraulic electro-valves applied in automotive industry, produced by different manufacturers. Such electro-valves are controlled by PWM signal (Pulse With Modulation) and are used to control oil pressure in automatic gearboxes. Paper includes some basic information about PWM signal with its application. In the subsequent chapter, there will be given information about tested valves, acquired by an individual elaboration, including design and the fundamentals of operation. In the followings sections, test bench is described and test results are presented. The temperature turned out as a very important factor which should be taken into account. In case of PWM controlling, for different temperatures some uncertainties of output pressure are possible. To avoid this undesirable phenomenon new control signal is proposed. Different characteristics of electro-valves are included: output pressure as the function of steering signal, the value of force exerted by the slider, responsiveness to a step function of request, regulation possibilities and internal leakages. What is more, occurrence of hysteresis phenomenon is checked. Based on test results a number of conclusions are formulated with some practical pieces of information for the engineers of mechanical systems which contain elements controlled by PWM signal.