Abstract. The OCCIE learning model (Orientation, Construct, Communicate, Improve, and Evaluate) is a scientific activity oriented chemistry learning model that is designed to improve the science process skills of students. The purpose of this study is to analyse the effectiveness of OCCIE learning model on chemistry learning to improve change the science process skillsof senior high school students. This research used one group pre-test and post-test design in XI grade chemistry senior high schools students of academic year 2018/2019. Students’ science process skillswere measured by using Science Process Skills Assessment Sheet (SPSAS) and Student Response Questionnaire (SRQ). The data analysis technique used Paired test and n-gain, The results of the study prove that: (1) There is an increase in science process skills of senior high school studentsat α = 5%; (2) The average score of n-gain of the students’ science process skills was in high category; and (4) Students responded very positively. Therefore, the OCCIE learning model on chemistry learning has proven to be effective to improve the science process skills of senior high school students.