Age-related dynamics and sex differences in the time of reaction to a moving object (RMO) were studied. The study involved 296 subjects from 3 to 28 years old. A total of 80 reaction time values were recorded for each subject. There was nearly a twofold decrease in RMO time with age. The boys, on average, had quicker reactions than the girls. Analysis of the distribution of individual parameters allowed us to disclose significant differences in the reaction time between the boys and the girls in all age groups.