Data characterizing the temperature dependence of the growth and CO2 emission of two species of xylotrophic fungi (D. confragosa and D. tricolor) during their development on wort–agar and wood debris in a laboratory experiment are presented. Currently available estimates of the temperature dynamics of CO2 emission by wood debris do not fully take into account the relationship between temperature, CO2 emission, growth, and respiratory activity of fungi. In the range of 10–30°C, both linear growth and CO2 emission activity of fungal mycelium are positively and linearly related to temperature (Spearman’s correlation coefficient, 0.94–0.97) to the same extent (Q10 of growth, 2.2; Q10 of respiration, 2.1), and CO2 emission is directly proportional to mycelium area and its specific emission activity. As a result, the temperature effect on CO2 emission is a derivative of two equally temperature dependent factors: growth and specific emission activity of mycelium. It is equal to the product of the effects of each of the factors separately and is described by an exponential equation, which reflects the non-additive, possibly synergistic nature of the temperature enhancement of CO2 emission in the range from 20 to 30°C.