Soil organic matter consists of various substances with different turnover times. To describe the heterogeneous nature of soil organic matter, multi-pool models have been developed. The ROTHC pool model has been widely used for various simulations of soil organic matter decomposition processes. ROTHC simulates carbon turnover and CO₂ production in the top soil layer without any spatial distribution in soil depth. Consequently, spatial variations in soil organic matter concentrations, soil moisture, temperature, and soil aeration can not be considered. Therefore, the ROTHC pool concept was integrated in the one-dimensional SOILCO2 transport model which physically describes water flow, heat flow, and CO₂ transport. Decomposition of the soil organic matter pools is usually described by first order kinetics with different decomposition rate constants. These constants are valid for optimal environmental conditions and are converted according to the actual environmental conditions by reduction functions. Soil temperature and moisture are considered as the most important variables for decomposition of soil organic matter. In this study we assess the influence of different temperature and moisture reduction functions on the simulation of CO₂ fluxes using a realistic scenario. For this purpose, the dataset of a respiration experiment on a wheat stand was chosen. The influence of different temperature reduction functions on the simulated cumulative CO₂ fluxes was very strong with deviations up to 41 % (1.77 t C ha^-1) for the six-month simulation period in 1981. The usage of different moisture reduction functions resulted in deviations of cumulative CO₂ fluxes up to 2 % (0.10 t C ha^-1). A combination of corresponding temperature and moisture reduction functions resulted in the highest deviations up to 41 % (1.80 t C ha^-1). The choice of both soil temperature and moisture reduction functions is a crucial factor for a reliable prediction of CO₂ fluxes.