This study aimed at identifying the level of scientific argumentation skills in chemistry subject among Omani Grade 11th students and the effects of their logical thinking skills and gender on this level. The study sample consisted of (400) male and female students selected purposely from one educational region in Oman. The study's instruments consisted of "Scientific Argumentation Skills Test" and "Logical Thinking Test." The study results revealed that the level of grade 11th students was moderate in argumentation skills and was low in logical thinking. In addition, there were statistically significant differences at (ρ 0.05) in scientific argumentation skills level due to gender in favor of female students. It also showed significant differences in logical thinking variable in favor of students with abstract thinking, and in the interaction between gender and logical thinking in argumentation level in favor of female abstract thinking. The study is important for Omani chemistry teachers because it gives an overview of the level of scientific argumentation skills and logical thinking skills among their students, which then helps the teachers in determining the next steps of the learning process by adopting appropriate teaching strategies.