Mercury is a metal naturally and widely present in the environment but human activities have greatly increased its amount in all environmental compartments. This element, under its organic form methylmercury, became a global environmental concern due to its high toxicity, its capacity to bioaccumulate in biota and to biomagnify in the food chain. In aquatic systems, mercury is present at low concentration which involves the development of “ultra-clean” sampling techniques and the use of analytical techniques adapted to the measurement of mercury at trace level. Conventional techniques based on punctual or automated measurements are generally time-consuming, do not take into account all system variability and require pretreatment steps. To overcome these limitations, the Diffusive Gradient in Thin film (DGT) technique is an alternative technique to sample metal species in surface waters. This technique developed in 1994 by Davison and Zhang allows the in situ measurement of kinetically labile metal species in aquatic systems. Basically, this technique consists of the mass adsorption of solutes from the aquatic system through a diffusive layer to a resin. The aim of this study is to develop passive samplers coupled to gaz chromatography-inductively coupled plasma-mass spectrometry (GC-ICP-MS) for the simultaneous measurement of inorganic mercury Hg(II) and methylmercury MeHg in surface waters. For that purpose, two types of DGT (home-made 3-mercaptopropyl functionalized silica gel and commercial spheron-thiol both combined with diffusive agarose gel) have been tested under controlled conditions for inorganic mercury and/or methylmercury solutions. Basic performance tests (blank control, thickness and time-series experiments) confirmed the applicability of these tools for the measurement of Hg(II) and MeHg in aquatic systems. Diffusion coefficients in the agarose gels have been jointly determined for Hg(II) and MeHg. Moreover, the inorganic mercury and methylmercury fractions trapped by DGT have been determined by using optimized GC-ICP-MS procedure after extraction and derivatization.