The purpose of the present study is to examine factors which influence organisational citizenship behaviour of nurses during the coronavirus disease 2019 pandemic (COVID-19). A total of 157 usable surveys were collected from nurses working in both the public and private health services in Bosnia and Herzegovina. A Partial Least Square-based Structural Equation Modelling approach was constructed to test the reliability and validity of both the measurement and the structural model. Affective commitment influences three dimensions of organisational citizenship behaviour whereas perceived organisational support has a significant and positive effect on affective commitment. However, perceived organisational support has a negative impact, creating emotional exhaustion and depersonalisation aspects to the nurses' burnout. A positive relationship between the perceived organisational support and diminished personal accomplishment of the nurses, contributing to the level of burnout found.