This study aimed to improve our understanding of users' cognitive processes based on think aloud protocols generated during the retrieval process of an online database. It analyzed think aloud protocols generated by participants while performing pre-defined tasks using an online database. The protocols were encoded using the open coding method. As the results, four broad categories including retrieval, system format, system functionality, and information were drawn, and 21 detailed categories were generated. Based on the results, suggestions for the design of online databases were provided.