PurposeDrawing on social exchange theory and the expectancy–value model, this study has two objectives. First, it sought to explore the mediating role of nurses’ self-concept and affective commitment between perceived organizational support (POS) and three different targets (organization, co-workers and patients) of organizational citizenship behavior (OCB). Second, it aimed to develop a better understanding of how nurses´ self-concept and affective commitment mediate the influence of POS on OCB directed toward different targets through sequential mediation.Design/methodology/approachA cross-sectional study was conducted with 229 nurses. This sample was representative of the nursing population based on several demographic characteristics. Data analysis was performed using partial least squares analysis.FindingsThe study revealed that nurses´ self-concept plays a mediating role between POS and OCB directed toward the organization, co-workers and patients, while affective commitment has a mediating effect between POS and OCB directed toward the organization and co-workers. Finally, the indirect influence of POS on OCB through nurses´ self-concept and affective commitment was significant only at the organizational level.Originality/valueThis study contributes to the extant literature by identifying the mediating role of nurses´ self-concept among social exchange constructs such as POS, affective commitment and OCB directed toward different targets.