This research studies the effects of an interactive multimedia mobile learning application on students' understanding of chemistry concepts. The Organic Chemistry Reaction Application (OCRA), a mobile learning prototype with touch screen commands, was applied in this research. Through interactive multimedia techniques, students can create and visualize the mechanistic steps of an organic chemistry reaction. Ninety-two students who were either assigned to a control or an experimental group participated in the research. Data collection included achievement in the pre- and posttest, and students' responses in a questionnaire that examined their perception towards the OCRA. The findings demonstrated that students' attitudes towards the OCRA were positive while their test scores have improved. It is concluded that the teaching and learning approach applied in the OCRA has engaged students in learning organic chemistry and develop their conceptual thinking, leading to deeper understanding of chemistry concepts. [For the complete proceedings, see ED579395.]