Purpose: The purpose of this paper is to ascertain the green-purchasing capabilities required to ensure the successful implementation of green-purchasing practices under the forces of institutional pressure. Specifically, this paper explores the green-purchasing capabilities of buyer firms under the influence of institutional pressures in supplier selection, development, collaboration and evaluation in support of environmental purchasing.Design/methodology/approach: Questionnaire survey method was used to gather data from 163 ISO 14001-certified manufacturing firms in Malaysia. Partial least squares was used for hypotheses testing.Findings: Green-purchasing capabilities, such as manufacturing, financial, intraorganisational and integration capabilities, have a significant positive effects on green-purchasing practices. However, innovation capabilities have no significant effect on green-purchasing practices. Regulation, customer and competitor pressure positively moderate the relationships between green manufacturing capabilities and practices.Practical implications: The paper highlights the importance of green-purchasing capabilities in enhancing the green-purchasing practices of firms. The findings that pertain to moderating effect could be used to assist policy makers, particularly in setting appropriate policies and strategies to improve green purchasing.Originality/value: Although more studies on green purchasing have been conducted in recent years, issues, such as the effect of green-purchasing capabilities on green-purchasing practices, are still unspecified. Besides, this study considers institutional pressure as the moderator when a model is constructed to exemplify the relationship between green-purchasing capabilities and practices.