The study aimed to develop valid, practical, and effective computer based material by using guided inquiry model to help senior high school students to master science process skill. The study is a developmental study by using ADDIE model and try out design by using one group pretest-posttest as the design. Learning material used on this study were lesson plan, handout, worksheet, computer-based media and assessment sheet for science process skills. Data collected by using validation, observation, tests and questioners while the data analysis technique used descriptive quantitative and descriptive qualitative. The results showed: (1) Learning material which were developed categorized as valid, (2) The practicality of learning material could be seen from  feasibility of lesson plan categorized as very good and students’ activities is in accordance with phase of guided inquiry model, (3) Effectiveness in terms of: (a) The science process skill increased with average N-Gain value is 0.82 with high category, (b) The students’ responds toward material and implementation of learning is positive with 86% students are interested.

Based on this study it can be concluded that computer based material development using guided inquiry model can be used properly to help senior high school studentsto master science process skill.