This data supporting the study Leaf wax n-alkane distribution and hydrogen isotopic fractionation in fen plant communities of two Mediterranean wetlands (Tenaghi Philippon, Nisí fen - Greece). A total of 452 samples; of these, the majority (229) were samples of fully developed leaves, collected from the apical, sun exposed sections of each plant. Similarly, 161 samples were collected from the base of the main stem (except for N. alba). All samples were collected during midday (ca 10:00 to 17:00), with mean air temperatures of 24-28°C (Nisí) and 28-29°C (TP) in summer, and 21-24°C (Nisí) and 26°C (TP) in spring in Tenaghi Philippon (TP) peatland (NE Greece) and Nisí wetland (NW Greece). Understanding of the n-alkane environmental controls and 2H-fractionation mechanisms of Mediterranean helophytic communities, as well as ascertaining the 2H-composition of their source water and its relation to the 2H-composition of precipitation. All leaf and lower stem samples come from different mature individuals of a species, sampled in close proximity, and complemented by a total of 47 soil samples collected at ca. 20 cm depth within each sampling station, from patches not directly exposed to sunlight to avoid potential 2H-fractionation bias due to intense soil water evaporation. Additionally, 10 surface water samples were collected from swamp areas in proximity of the sampling stations at both sites. δ2H values of the 10 surface water samples were obtained using LGR LWIA-24d. Delta values are given as permil deviation from VSMOW (±1‰). Leaf, stem, and soil water was extracted through cryogenic vacuum distillation and its isotopic composition was measured using a TC/EA-MS via a Conflo IV interface; expressed as permil deviation from VSMOW and the long-term external precision was found to be ±0.8‰ (standard deviation). The n-alkanes of leaf, stem and soil samples were extracted via ASE, separated by increasing polarity, analysed via GC-MS, and quantified using an external standard. The n-alkane δ2H values of leaf and stem samples were determined using GC-irMSThe overall analytical uncertainty (pooled sample size weighted standard deviation) was found to be ±1.7‰.