Introduction: This study proposes a theoretical framework for the complex interplay between knowledge gap and perceived risk as motivators of information seeking. Given the shortage of studies that use quantitative research methods to support theory-building in information behaviour research, the survey method is adopted and two models with alternative configurations are examined. Method: Since the two proposed models involve relationships between latent constructs, survey items were developed to operationalise the constructs and statistical tests were performed to examine the associated hypotheses. Data were collected from a large public university through a scenario-based online survey. In order to avoid confounding effects, participants were recruited from a variety of educational levels, age groups, and socioeconomic backgrounds. Eight scenarios were randomly assigned across the participants. A total of 289 responses were used for analysis. Analysis: The two models were tested using partial least squares structural equation modelling (PLS-SEM), a commonly used method for theory development in exploratory social sciences research. Results: In model one, where perceived risk and knowledge gap are assumed to have direct effects on motivation to seek information, both direct effects are significant. In model two, where perceived risk is assumed to have a moderating effect on the relationship between knowledge gap and motivation to seek information, knowledge gap interacts with perceived risk to motivate information seeking. Given that model two has a better fit than model one, the results indicate that perceived risk and knowledge gap play a rather complex role in information-seeking behaviour. Model two proposes the risk-gap interaction hypothesis (RGIH), which states that risk perceptions interact with knowledge gap to motivate information seeking. Conclusions: The findings suggest that, in the presence of the interaction between perceived risk and knowledge gap, as suggested by the risk-gap interaction hypothesis, the well-established direct effect between knowledge gap and motivation to seek information becomes insignificant. Therefore, the interaction between perceived risk and knowledge gap is of primary importance in motivating information seeking.