Taekwon-do ITF (International Taekwon-do federation) is a kicking type of combat sports. Detailed biomechanical analysis of Taekwon-do techniques is necessary for proper teaching of this sport. The aim of the study is investigation of the biomechanical structure of Taekwon-do ITF side kick. Investigating biomechanical structure of the kick, scientific publications in biomechanics of karate, taekwondo WTF, kickboxing and football (socker) were analysed. 10 blue- and green-belt level Taekwondo athletes participated in the study (age: 12-14 years; body height: 150-162 cm; bodyweight: 38-52 kg; experience in sports: 3-5 years). Side kicks were videorecorded using two highspeed Basler videocameras (100 Hz), SIMI Motion software was used for data analysis. Taekwon-do side kick of 12-14 years old Taekwondo athletes lasts 1,24 s, excluding preparation phase. The kick consists of four phases – preparation phase, kicking phase (0,33 s), target contact phase (0,15 s), and post-kicking phase (0,76 s). Further training process will be aimed on development and mastering of kicking phase (loading and kick execution) speed capabilities.