This study examines determinants of a knowledge transfer between external experts and members of an organisation in order to facilitate enhancement of the organisation's knowledge base. An organisation's ability to acquire, integrate, store, and share organisational knowledge and expertise are seen as an essential strategic capability (Grant, 1996b). This study attempts to examine organisations' ability to capture external expert knowledge by linking the use of external experts to business level strategy. More specifically, by applying a knowledge-based perspective, this study examines how the quality of personal interaction and the complexity of the transferred knowledge affect the extent of knowledge gain to the organisation. Quality of personal interaction is indicated by the (1) frequency of interaction, (2) closeness of communication, and (3) trust in the external expert to be reliable. Knowledge complexity is indicated by the (a) level of codification, (b) degree of dependence, and (c) need for modification of the transferred knowledge. It is hypothesised that quality of personal interaction affect the extent of knowledge gain, and that the effect of quality of personal interaction on knowledge gain is moderated by the complexity of the knowledge to be transferred. The hypothesis were examined on a sample of 46 internal workers in 3 organisations who had to interact with external experts. The empirical findings show that quality of personal interaction may be a better indicator of the outcome of a knowledge transfer than the complexity of the knowledge (p<O.05), and that the influence of quality of personal interaction is not moderated by the level of knowledge complexity. This study makes a contribution to the work in the area of knowledge management by clearly defining and measuring central theoretical constructs such as quality of personal interaction, knowledge complexity and knowledge gain. This study also adds to our understanding of employment externalisation by addressing how external experts are to be used to increase the knowledge gain to the organisation. For practice, these results highlight the important role of personal interaction and especially the roles of communication and trust in a working relationship. Directions are suggested for future research on externalization and knowledge capturing processes, such as knowledge acquisition, integration, and sharing.