Recent research have aimed to know the effect of rational inquiry strategy on acquisition basic science processes for second intermediate students in physics. To verify the aim of this research , the researchers added the following zero hypotheses : No statistically significant differences at the level of significance (0.05) between the students mean scores of the two groups on basic science Processes test. The research was carried out on the second intermediate grade male students in Alam Al Yakeen school in Baghdad; belong to Education Directorate Al- Karkh/2, for the Academic Year (2014-2015) A.D. Prepared research requirements included ] selected the scientific subject chapters (6,7,8,9) from physics textbook, the formulation of behavioral objectives, prepared instructional plans for the experimental groups and control groups[ , after the presentation to a group of specialists . The researchers applied research tools by themself, and he adopts basic science processes test for (Qaisi ,2012) within the limits of his research, consists of (24) items of multiple choice and alternatives (4) by (8) paragraphs for each mental process, namely, (observation, measurement, classification, inference, prediction, communication, use of numbers, use the relationships of space and time). The research sample was selected intentionally by the researcher which consisted of (69) male students, randomized into two groups (35) students in experimental group and (34) students in control group. The two groups students have been equalization by the following variables: (Pre physics knowledge, physics scores at mid-year, age in month, basic science processes pre- test). Experimental group students studied by using rational inquiry strategy and the control group students studied by using traditional method, one of the researchers studied the two research groups by him two lessons per week. Research tool, were applied, basic science processes test to the students of the two groups, after completion the study of Physics chapters under research. Statistical tools used to deal with the results. The results showed (There is a statistically significant difference) between the experimental & control group students on basic science processes test, favor the experimental group students. According to mentioned above , the researchers had a number of recommendations which including to use in rational inquiry strategy teaching physics. In light of the results, researchers suggested a researcher that made conduct the effect of " rational inquiry strategy" on other variables and its effect on other science subjects