An ongoing argument in the MetA literature is that the human factor has an important impact on the outcome of those operations. Analysis of the HR integration has identified human factors that play an inhibiting role on post-acquisition performance, particularly cultural and organisational mismatch, resistance to change and poor level of strategic integration planning. Yet, less is known about the role of the human factor in the organisational dynamics, which is at work when merging two autonomous entities, and the related impact on performance. The aim of the paper is to study ways of exploring the relationship between the human factor and post-acquisition performance, in discussing possible contributions from a knowledge-based view of the firm (KBV) and complexity theory