This study was conducted to explain the effect of thematic based integrated science learning to the student's critical thinking skills and character. One group pretest-posttest design is involving thirty students in one of the junior high school in the Palu city. A sample was taken using purposive sampling. Data of critical thinking skills obtained from pretest and posttest, whereas the characters students are collected with observation and questionnaire. The results showed critical thinking skills of students are better after following thematic-based integrated science learning with N-gain as 0.52. Ten characters of students showed good category with the lowest scores on the aspects of environmental concern. The study revealed that thematic based integrated science learning can increase of critical thinking skills and character of the seventh grade junior high school students with good category.