: The aims of this study were to investigate the difference of students\u27 nature of science understanding who were taught using 5E learning cycle model with SSI learning context and conventional model on buffer solution and salt hydrolysis. This study used quasi-experimental with pretest and post-test design. The sample considered two classes and selected by convenience sampling technique in SMAN Tulungagung. The data were obtained using the questionnaires nature of science Likert scale (R = 0.883) and analyzed by one way ANCOVA and effect size. The research results showed significant different on students\u27 nature of science understanding between students who were taught using 5E learning cycle model with SSI learning context and students who taught using conventional model. Based on effect size, nature of science aspects that large contribute was the scientific method, empirical, inference, social dimension of science, and Social and cultural embeddedness of science. Aspects of the nature of science that medium contributes was tentative, creative, and theory driven. While the theory and law were small contribute