This paper builds upon the theoretical framework developed by Zahra and George [Absorptive capacity: a review, reconceptualization, and extension. Academy of Management Review 2002;27:185–203] to empirically explore the antecedents of potential absorptive capacity (PAC), i.e. the ability to identify and assimilate external knowledge flows. Based on a sample of 2464 innovative Spanish firms, we find evidence that R&D cooperation, external knowledge acquisition and experience with knowledge search are key antecedents of a firm’s PAC. Also, during periods of important internal reshaping, when there are significant changes in strategy, design of the organization and marketing, firms exert more effort to accumulate PAC. Finally, we find that PAC is a source of competitive advantage in innovation, especially in the presence of efficient internal knowledge flows that help reduce the distance between potential and realized capacity.