The Church of Psilomethoxin claims to produce a novel tryptamine by adding 5-MeO-DMT to the substrate of cultivated Psilocybe mushrooms, which is then biosynthesized into psilomethoxin, the church’s sacrament. In this study, we investigate the validity of this claim using comprehensive analytical techniques, namely ultra-performance liquid chromatography with high-resolution mass spectrometry (UPLC-HRMS). Authentic reference standards for structurally related tryptamines were used for comparison. Our findings revealed no evidence to suggest that the compound psilomethoxin is present in samples of material that the church is offering to their members online. Psilocybin, baeocystin, and psilocin, were, however, unambiguously identified in the sample, suggesting that the claims regarding the biosynthesis of psilomethoxin may be misguided. The implications of these findings should be critically considered within the context of public health and safety