The aim of this study was to determine how carbon (C) mineralization of acacia (Acacia cyanophylla, Fabaceae) soil are affected by the different temperature (23 degrees C and 28 degrees C) and humidity (80% and 60% of their field capacity) conditions in the laboratory. The acacia soils were collected from Cukurova University campus in the eastern Mediterranean region of Turkey. C mineralization of all soils was determined using CO2 respiration method. The microbial activity increased together with temperature increases. The microbial activity in the soils humidified to 80% of field capacity was significantly different from field capacity and 60% of field capacity at both 23 degrees C and 28 degrees C temperatures (p<0.001). The ratios (%) of C mineralization of 80% of field capacity at 23 degrees C and 28 degrees C were also significantly higher than all of the others (p<0.001). These findings might Suggest that 80% of field capacity of acacia soil is; better humidity for microbial activity at both 23 degrees C and 28 degrees C temperatures into 30 days.