The purpose of this study is to determine the differences in learning outcomes and science process skills of students learned with Project Based Learning and Discovery Learning models on acid-base material, as well as the correlation between students' science process skills and student learning outcomes. This research is a quantitative research. The samples in this study were taken by random sampling of 2 classes, namely XI MIPA 1 as experimental class I and XI MIPA 3 as experimental class II, where each class was taken by 29 students based on the similarity of pretest results. The instruments used are test instruments in the form of multiple-choice questions and essays and non-test instruments in the form of observation sheets. Hypothesis testing was carried out using the SPSS Statistic version 24 for Windows computer program using the Independent Sample T-Test and Bivariate Pearson Correlation. For hypothesis I obtained the value of sig. (2-tailed) 0.008 (0.05) so that Ha is accepted, which means that there are differences in student learning outcomes learned with Project Based Learning and Discovery Learning models on acid-base material. For hypothesis II obtained sig value. (2-tailed) 0.010 (0.05) so that Ha is accepted, which means that there are differences in students' science process skills learned with the Project Based Learning and Discovery Learning models on acid-base material. For hypotheses III and IV obtained sig values. (2-tailed) of 0.002 and 0.001 (0.05) so that Ha is accepted, which means that there is a correlation between students' science process skills and student learning outcomes learned with Project Based Learning and Discovery Learning models on acid-base material.