This research was aimed to describe the effect of socioscientific issues in improving critical thinking ability on electrolyte and non-electrolyte solutions. The cluster random sampling technique was used for the selection of samples, obtained X IPA 1 as experimental class and X IPA 4 as control class. The method is quasi-experimental design with a pretest posttest control group design. The effect of socioscientific issues was analyzed by the differences of two averages on n-Gain and the effect size test. The results of the study showed that the n-Gain average of students critical thinking ability in the experimental class was high , and the effect size was large. The conclusion of this research is that socioscientific issues based learning has a positive effect in improving critical thinking ability in electrolyte and non-electrolyte solution material.Keywords: socioscientific issues, critical thinking ability, electrolyte and non-electrolyte solutionsPenelitian ini bertujuan untuk mendeskripsikan pengaruh isu sosiosaintifik dalam meningkatkan kemampuan berpikir kritis pada materi larutan elektrolit dan non-elektrolit. Teknik cluster random sampling digunakan untuk pemilihan sampel, diperoleh kelas X IPA 1 sebagai kelas eksperimen dan kelas X IPA 4 sebagai kelas kontrol. Metode dalam penelitian ini yaitu kuasi eksperimen dengan desain penelitian pretest posttest control group design. Pengaruh isu sosiosaintifik dianalisis menggunakan uji perbedaan dua rata-rata pada n-Gain dan uji effect size. Hasil penelitian menunjukkan bahwa rata-rata n-Gain kemampuan berpikir kritis siswa pada kelas eksperimen berkriteria ‘tinggi’, dan effect size ‘besar’. Kesimpulan penelitian ini yaitu pembelajaran berbasis isu sosiosaintifik berpengaruh positif dalam meningkatkan kemampuan berpikir kritis pada materi larutan elektrolit dan non elektrolit.Kata kunci: isu sosisaintifik, kemampuan berpikir kritis, larutan elektrolit dan non-elektrolithttp://dx.doi.org/10.23960/jppk.v8.i2.201907