The proliferation of green marketing claims in India's rapidly expanding eco-tourism sector has created a paradox: while environmental branding attracts sustainability-conscious travellers, it simultaneously triggers consumer scepticism when claims appear performative rather than substantive. This study investigates the psychological mechanisms through which green marketing authenticity — and its perceived absence (greenwashing) — influences consumer trust, purchase intention, and word-of-mouth (WOM) behaviour in the context of eco-resort marketing in Kerala, India. Drawing on Attribution Theory (Kelley, 1967; Weiner, 1985), Value-Belief-Norm Theory (Stern et al., 1999), and Signalling Theory (Spence, 1973), this study develops an eighthypothesis conceptual model that positions green authenticity as the central construct mediating the relationship between ecomarketing stimuli and consumer behavioural outcomes. Third-party eco-certification and prior eco-resort experience are proposed as moderating variables, while consumer environmental values serve as a second moderator of the authenticity–trust pathway. A quantitative survey methodology is proposed, targeting 400 domestic and NonResident Indian (NRI) tourists who have visited Kerala eco-resorts in the preceding 24 months. Partial Least Squares Structural Equation Modelling (PLS-SEM) will be employed for hypothesis testing, with Common Method Bias assessed through Harman's single-factor test and confirmatory factor analysis. This study contributes to the nascent but rapidly growing literature on hospitality greenwashing scepticism by: (a) introducing the green authenticity construct as a distinct psychological mediator; (b) providing the first empirical examination of eco-resort greenwashing scepticism in an Indian context; and (c) offering sector-specific insights for eco-resort operators in Kerala on how genuine environmental practice translates into measurable commercial outcomes.