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.