Service robots, autonomous agents combined with artificial intelligence, have gained significant momentum in retail industry. Research on service robots has been attracting increased attention across various disciplines, with focuses on technical issues, benefits, and adoption/acceptance. However, little is known about consumer reactance to service robots and its psychological mechanisms. This study, based on reactance theory, examines how perceived threat to freedom triggers consumer reactance, and how psychological inertia moderates this process. In doing so, this study identifies a model of reactance to service robots by comparing two existing reactance models. A survey of 352 US consumers who used service robots for in-store shopping was conducted. This study found that consumer reactance to service robots is best explained by a dual-process cognitive-affective model. Increased threats to freedom drive resistance intentions both directly and indirectly through negative cognition, and psychological inertia moderates this process. The findings contributes to the literature by highlighting the adverse aspects of new retail technology and presenting a model of consumers' reactance to service robots. This study offers practical insights into what to consider in designing consumer-service robot retail environments to reduce reactance.