BACKGROUND: Portable and cost-effective accelerometers can yield instantaneous results of force, power, and velocity, with minimum set-up time to assess muscle power. However, such devices must also produce both valid and reliable data. OBJECTIVE: The current study assessed the validity and reliability of the Myotest Pro wireless accelerometer (ACC). METHODS: Thirty physically active males performed two squat jump, on two separate sessions. The jump was recorded simultaneously by a force platform and ACC, which was attached to a barbell resting on the subjects' shoulders. Validity was determined using Pearson correlation coefficient (r) and t-test between the maximum force platform (F-FP) and ACC (F-ACC) force. Between session reliability of F-ACC, power (P-ACC) and velocity (V-ACC) from the ACC were assessed with t-test, intraclass correlation coefficient (ICC), and coefficient of variation (CV). RESULTS: F-ACC correlated highly to F-FP (r = 0.815, p < 0.05), but there was a proportionate ratio bias of 0.81. There was no difference between sessions (p > 0.05) for any variable. High ICCs were found for all variables (F-ACC 0.90; P-ACC 0.80; V-ACC 0.84). Low CV was found for F-ACC (2.1%), P-ACC (3.3%) and V-ACC (3.2%). CONCLUSIONS: ACC is a valid and reliable tool to use for assessing barbell movement, but caution in power data interpretation is needed.