Surface coal mining of coal causes drastic landscape disturbances and severe soil degradation. Reclamation could restore soil quality and ecosystem productivity. A study was conducted to evaluate the effects of age since reclamation on different biological and chemical fractions of soil organic C and N. Microbial biomass C was determined by chloroform fumigation, followed by incubation for 10 days. Head-space gas samples were collected and analyzed at 3, 6 and 10 days for the fumigated non-fumigated samples. After 10 days, non fumigated samples were further incubated for 60 days with weekly gas sampling. Gas samples were analyzed by GC for CO₂, CH₄ and N₂O. In addition, samples were treated by sodium thiosulphate, sodium hypochlorite, and hydrogen peroxide. Microbial biomass and microbial mineralizable C in the top 0-10 cm depth ranged from 0.17 to 0.320 and 0.42 to 1.35 mg g^-1 of soil respectively, and increased with increasing age since reclamation. Biological OC fraction was generally correlated with oxidation fraction. Results indicate that microbial biomass C could be used as an indicator of ecosystem restoration.