The CSIRO Global Atmospheric Sampling Laboratory (GASLAB) Flask Sampling Network archive for the atmospheric trace gas hydrogen (H2) concentrations. GASLAB principally analyzes air samples that have been captured at eleven fixed geographic sites and one moving (aircraft over bass strait and Cape Grim), but also includes other sites at various locations globally on a less regular or as needed basis. The flask air sample is analyzed for the 5 atmospheric trace gases Methane (CH4), Carbon Dioxide (CO2), Carbon Monoxide (CO), Hydrogen (H2) and N2O (Nitrous Oxide). Data about the relative concentrations of these are particularly important for Global Warming studies as CO2 and CH4 are the two most effective anthropogenic greenhouse gases; CO and H2 influencing concentrations of the hydroxyl radical (OH), thereby affecting the main sink for atmospheric CH4. H2 is produced in a sequence of reactions following the reaction of OH with CH4. Measurements for H2 concentrations are made through the use of a Gas Chromatograph with a mercuric oxide reduction gas detector “RGA3-1” (R1). There are 6 differant types of flask that are used to store and transport air samples from site and in the labratory:(i) glass 0.5 litre ("G050"), (ii) glass 5.0 litre ("G500"), (iii) glass 0.8 litre ("G080"), (iv) electropolished stainless steel 1.6 litre "Sirocans" ("S160"), (v) glass 2.0 litre, 1 stopcopck ("F", "FF", "FA", "FE", "EP", ALT"), (vi) glass 2.0 litre, 2 stopcocks(“M1”, “S”, “P2”, “TEMP”). Files containing a single species value for each sample are denoted by a filename of the form (XXX_XXXX_event.XXX), for the geographically fixed sites data is also provided in the form of monthly means (e.g. XXX_XXXX_mm.XXX) with all fies being in ascii format.