Despite the important contribution made by green human resource management (GHRM) towards organizational citizenship behavior for the environment (OCBE), few published studies have investigated this significant contemporary topic in the hospitality industry, which constitutes a major gap in the literature on the greening of the hospitality industry. Drawing on Ability-Motivation-Opportunity theory, this study develops and tests direct and interactive effects of GHRM practices on OCBE. A mixed methodology is applied, with a survey of 203 employees working in 4–5 star hotels being conducted first to test six hypotheses, followed by qualitative research into two specific cases. The results indicate a mixture of expected and unexpected findings, including: (i) the direct effects of GHRM practices on OCBE; (ii) the interaction of three GHRM practices (training, performance management and employee involvement), which can enhance employees' voluntary green behavior, dependent on the level of green performance management and green employee involvement; and (iii) that green training is seen as a key mechanism to boost employees’ voluntary green behavior. The originality of this manuscript is based on its status as one of the first mixed-methodology works on GHRM in the hospitality industry in an emerging economy. •There is currently a lack of studies on green HRM in the hospitality industry.•We conducted a mixed-methods study on this topic.•We covered the direct influences of GHRM practices on OCBE.•We explored interactive influences of GHRM practices and OCBE.•We extended Ability-Motivation-Opportunities theory in the green context.