The purpose of this study was to design and validate an observation instrument for the analysis of the performance parameters related to the smash in padel. Eleven experts, who had to meet four of the five inclusion criteria, participated in the process. Aiken's V coefficient and confidence intervals were used to calculate content validity and Cronbach's α coefficient to analyze reliability. The adequacy and writing of the eighteen items initially designed were evaluated. Four variables were eliminated due to obtaining values ​​<.87 in Aiken's V coefficient for adequacy. The rest of the variables were modified in their wording, according to the qualitative evaluations of the experts, or were considered correct. The reliability of the instrument was acceptable, (α=.82). The OASP instrument is very new, as it is of interest for analyzing the use and effectiveness of the padel smash.