This paper reports a study into the nature, dynamics and effects of the ‘chemistry’ of the Chairman/Chief Executive Officer (CEO) relationship. A qualitative, semi-structured interview, narrative analysis methodology over a twenty-eight month period was adopted. A sample of CEO’s, Chairmen and Non-Executive Directors (NEDs) across the boards of nine corporations, agreed to participate in in-depth discussion. Personal narratives of the board director’s experience, particularly from the perspective of enabling understanding of the ‘chemistry’ of the Chairman/CEO relationship, were analysed in terms of boardroom and organisational effect. There are two elements to ‘chemistry’, analytical interpretative capacity (sense making) and deep friendship (philos). Both emerge as primary to determining Chairman/CEO effectiveness and in combination nurture meaningful knowledge sharing as well as a desire for learning in the boardroom. Absence of either allows for a workable relationship, but with neither, the Chairman/CEO dyad and the organisation are harmed. This qualitative study draws attention to the criticality of sense making and philos as determinants of the quality of the Chairman/CEO relationship. The study results emphasise the critical nature of the Chairman/CEO relationship in determining boardroom and organisational effectiveness. Development of this dyadic interaction is considered to positively benefit boardroom dynamics and organisational performance