This paper analyzes the effects of open access (OA) on the creation of scientific knowledge. In a first step, drawing on the theory of Nonaka and colleagues, their SECI model is applied to the processes of knowledge creation in science. Typical activities of the research process are assigned to the four knowledge conversion modes socialization, externalization, combination, and internalization. Subsequently, on the basis of the resulting framework it is shown how OA affects scientific knowledge creation. We conclude that (1) with regard to the epistemological dimension of knowledge, OA decreases the time of running through the SECI cycle, and (2) concerning the ontological dimension, OA enlarges the number of possible receivers of newly created knowledge. Those propositions provide a basis for further empirical studies within the introduced framework.