The study explores relationships between the peat decomposition rate and moisture-temperature conditions. Decomposition was evaluated through studying microbial production of CO2 and CH4. Decomposition of the original peat substrate (peat) was compared to one of the peat-sand mixture from 5 year old urban lawn (mixture). In the research the CO2 and CH4 emissions were studied under following temperatures and moisture conditions: temperature – 5 °C, 10 °C, 15 °C и 40 °C and moisture – 30%, 60%, 120%, 300%. The obtained results showed significant correlations between moisture and temperature conditions and CO2 and CH4 emissions. Differences of moisture and temperature impacts on the soil organic carbon (SOC) decomposition in the peat and peat-sand mixtures were observed as well. The CO2 emissions from the peat-sand mixture were higher compared to the peat, whereas SOC content in both substrates was similar.