Molecular hydrogen (H₂) is a highly reactive volatile that plays a fundamental role in Earth's evolution. In situ Raman spectroscopic analysis of H₂ in natural inclusions offers crucial insights into its behavior during geological processes. However, H₂ preservation within inclusions remains poorly constrained. Here, we demonstrate the formation of H₂ within natural gas and aqueous inclusions in fluorite, dolomite and quartz, and synthetic fused silica capillary capsules containing CH₄ and carbonaceous materials during Raman spectroscopic analyses at ambient temperature. Under laser irradiation (with wavelengths of 473 nm, 532 nm and 633 nm), common carbonaceous materials (e.g., pyrobitumen, graphite, and diamond) catalyze CH₄ decomposition, producing H₂ within seconds to tens of seconds. This photocatalytic reaction may lead to false-positive identification of H₂ as a primary fluid inclusion component. Our findings emphasize the necessity of preventing artificial H₂ generation during fluid inclusion studies to avoid misinterpretations of the inferred water/H₂ cycle and the physicochemical conditions governing H₂ percolation in subduction zones and magmas.