This study uses a real-effort survey experiment to investigate whether expressions of gratitude induce reciprocal behaviour and hence significantly increase individuals’ effort. I extend existent literature by exploring non-pecuniary gifts that signal different degrees of gratitude, all combined with an interpersonal element. Based on a formal model, I hypothesize that a greater amount of gratitude is accompanied by higher levels of provided effort. The results show that appreciation in form of a thank you note positively affects reciprocal effort choice, compared to receiving no gratitude. An even higher level of gratitude conveyed in form of a video clip, however, does not impel subjects to provide more effort. Moreover, while I detect women to behave more reciprocally than men, this effect is least present in the gratitude treatments. These insights provide valuable implications for experimental research as well as for organizations and modern labour markets, emphasizing that non-monetary gifts, such as expressions of appreciation, are a cost-effective tool for human resource management to determine workers’ effort.