Results of author’s research work on the determining of driver reaction time, carried out on a prototype test machine “autoPW T”, have been presented. The machine was built at the Faculty of Transport of the Warsaw University of Technology and it can be used for performing tests known from typical laboratory “psycho-technical examinations” (reaction time measurements on “reflex testers”) on the one hand and, on the other hand, for evaluating driver’s reactions at the operation of real vehicle controls (steering wheel as well as brake, accelerator, and clutch pedals) during a simulated drive with a prescribed speed. Apart from a brief description of the test machine and its capabilities, results of the examination of about 100 drivers have been presented, which included a comparison of the reaction times measured for the steering wheel and brake pedal being operated. The measurement results quoted were obtained from four different tests, i.e. the testing of simple reaction on the steering wheel, simple reaction on the brake pedal, complex reaction, and reaction at emergency braking. They have been shown in the form of histograms of the average values and standard deviations of the reaction times and other statistical parameters of the distributions obtained for the whole population of the drivers examined. Differences in the reaction time values depending on specific test types, with reference to the central measure of the distribution (average value) and the measure of dispersion of the distribution (standard deviation value), have been pointed out.