Purpose-The purpose of this paper is to investigate the impact of exchange modes-negotiated, reciprocal, generalized, and productive-on inter-employee knowledge sharing. Design/methodology/approach-Based on the affect theory of social exchange, a theoretical model was developed and empirically tested using a survey of 691 employees from 15 North American credit unions. Findings-The negotiated mode of knowledge exchange, i.e. when a knowledge contributor explicitly establishes reciprocation conditions with a recipient, develops negative knowledge sharing attitude. The reciprocal mode, i.e. when a knowledge donor assumes that a receiver will reciprocate, has no effect on knowledge sharing attitude. The generalized exchange form, i.e. when a knowledge contributor believes that other organizational members may reciprocate, is weakly related to knowledge sharing attitude. The productive exchange mode, i.e. when a knowledge provider assumes he or she is a responsible citizen within a cooperative enterprise, strongly facilitates the development of knowledge sharing attitude, which, in turn, leads to knowledge sharing intentions. Practical implications-To facilitate inter-employee knowledge sharing, managers should focus on the development of positive knowledge sharing culture when all employees believe they contribute to a common good instead of expecting reciprocal benefits. Originality/value-This is one of the first studies to apply the affect theory of social exchange to study knowledge sharing.