ABSTRACT ? The purposes of this research were to know: 1) the influence of Guided Inquiry learning model toward science process skills, 2) the influence of academic ability toward science process skills, 3) the interaction between Guided Inquiry learning model and academic ability toward science process skills. The research was quasi experiment research. The research was designed using posttest only control group design by using the experimental classes (application of Guided Inquiry learning model) and control classes (conventional learning. The populations of this research were all of 10th degree students at SMA Negeri 5 Surakarta in academic year 2011/2012. The samples of this research were the students of X-4 as experiment group and X-2 as control group. The sample of this research was established by cluster random sampling. The data was collected essay test, observation form, and document. The hypotheses analyzed by Two-Way Anava. The research concluded that 1) application of Guided Inquiry learning model had significant effect toward science process skill, 2) the academic ability didn?t has significant effect toward science process skill, 3) there was interaction between Guided Inquiry learning model and academic ability toward science process skills. Keywords: Guided Inquiry, Science Process Skills, Academic Ability