Caffeine is the most prevalent in the last two decades, as it is used to improve cognitive and motor performance during training; it is an aid in generating energy for athletes. The reaction time is affected by hesitation and exaggerated waiting during the competition. This insufficiency is caused by the poor level of abilities of the players, as the reaction time is one of the indicators of success in karate. This study aimed to investigate the effects of caffeine on the level of reaction during specific karate combat class Kumite on the skills (Kisami Zuki, Gyaku Zuki, Mawashi-Geri, and Ura Mawashi Geri) and compare it with the placebo. The researchers followed the quasi-experimental approach, and the study was conducted on a sample consisting of eight Karate players of real combat class Kumite; the mean and standard deviations of the basic measurements of the sample are as follows: age: 19.75 + 2.12, height: 173.87 + 7.7, mass: 70.5 + 10.58, training age: 12.37 + 3.66. The amount of caffeine was determined as 6 mg/kg, and the procedures were carried out without the knowledge of the study sample by taking caffeine or placebo, where the players took placebo on the first day of the measurement, and caffeine on the second day. The results showed that there were statistically significant differences in the level of reaction in the skills under study between taking caffeine and placebo, where the percentage of improvement in the skill of Kisami Zuki (13.63%) in favor of caffeine intake, the improvement percentage for Gyaku Zuki skill was (10.63%) in favor of caffeine intake, the improvement percentage for Mawashi-Geri skill (12.76%) in favor of caffeine intake, and the improvement rate for Ura Mawashi Geri skill (13.72%) in favor of caffeine intake. In conclusion, there is a need to increase the interest of Karate officials in educating players and coaches about the importance of using nutritional supplements, especially caffeine, in the specified and permitted dosage to improve the reaction time during the Karate competitions. Keywords: caffeine, reaction, kumite, karate. https://doi.org/10.55463/issn.1674-2974.50.2.12