This study proposes a model for co-creation behaviour in online social networks, grounded in Service-Dominant (S-D) Logic and informed by the Stimulus-Organism-Response (S-O-R) model. Current attempts to conceptualise factors for characterising the customer value co-creation behaviour fall short in that they have not adequately explored the environmental and cognitive factors towards an effective co-creation behaviour in actor-to-actor (A2A) service ecosystems. This research identifies critical factors related to value co-creation behaviour on co-created services delivered through service-oriented social networks (SOSNs). The study reviews the extant co-creation-related articles published from 2002 to 2015, with a focus on important environmental and cognitive factors in the S-D logic. A conceptual model is presented that comprises of environmental factors (Network Structure, Service Platform Capabilities, Roles and Social Influence), customer value perception (cognitive, social and personal integrative and hedonic values) and value co-creation behaviour (Participation and Citizenship Behaviour). The model provides a scale for validation of co-creation behaviour based on the identified behavioural and cognitive characteristics. It might be used as a tool for the development of the future business models and the design of future architectures of participation on different utility platforms helping practitioners to develop a better understanding of customer behaviour on SOSNs.