The assessment of net ecosystem exchange (NEE) and respiration of ecosystem (Reco) of terrestrial ecosystems is necessary to improve our knowledge about the carbon cycle. The aims of this paper were to present reliable measurements of CO₂ fluxes of a temperate bog ecosystem located in Poland using a closed dynamic chamber system and to obtain a daily dynamic course of CO₂ fluxes over the 2007 vegetation season. Measurements of CO₂ fluxes were carried out at Rzecin peatland ecosystem located in northwestern Poland using the set of two chambers (dark and transparent). Reco during the experiment period ranged from 2.65 to 14.76 μmolCO₂·m^-2·s^-1. The daily run of NEE was inversed to PPFD and the values of NEE varied from 0.06 to -11.82 μmolCO₂·m^-2·s^-1. We found differences between NEE and Reco in the wetland ecosystem with respect to term of measurements. The PPFD, air and soil temperatures explain most temporal variability of CO₂ fluxes at Rzecin. But vegetation structure, its phenology and water-level depth seem also to play important roles. The chamber technique is a useful tool for determining carbon dioxide exchange between wetland surface and the atmosphere.