Scientific argumentation is a higher-order thinking skill that is a major focus in education in the 21st century. This is a skill that plays an important role in knowledge construction which in reality is rarely implemented in science learning. The facts show that most students have low scientific argumentation skills and still need to be improved. In improving scientific argumentation skills, the learning design used must give students more opportunities to build and criticize arguments, make claims, and use evidence in the process of reasoning based on inquiry activities. Based on the results of previous research, it is known that inquiry-based learning has extraordinary potential in developing students' scientific argumentation skills. Interestingly, no research has been found that reveals the effect of inquiry-based online learning on students' scientific argumentation skills. Therefore, this study aims to determine the impact of inquiry-based online learning with a virtual laboratory on students' scientific argumentation skills. This study uses a onegroup pretest-posttest design with n-gain analysis. The results of this study indicate that the application of inquiry-based online learning with a virtual laboratory can improve students' scientific argumentation skills. Uniquely, this only significantly impacts the claim, evidence, and reasoning components, but not the counterclaim and rebuttal components.