The aim of this study is to determine the existence of science process skills (SPS) on the topic of reaction rate. The research design used survey as the methodology. The sample contained 40 students from Grade 11 at one senior high school in Karanganyar, Indonesia. The science process skills of the students were assessed using a performance assessment and observation sheets. The instrument used for performance assessment is a rubric that consists of descriptions of four levels of performance, comprising low, medium, high and very high. The science process skills assessed were observing, data recording, communicating, inferring, experimenting and data interpreting. Results showed that the highest value for science process skills was achieved in communication and the lowest in data recording.