The preservative characteristics of chlorinated coconut oil were studied. The killing point of fungi Fomes sp., Poria vincta and Polyporus cinnabarinus, was 0.02%, 0.07% and 0.10% respectively, in malt agar (25 mg malt extract and 15 mg agar per 1000 ml distilled water) but 0.088%, 0.14%, and higher than 0.14% concentration respectively in agar-block test. BAgtikan blocks measuring 1-1/4 x 1/2 x 1/4 were subjected to fungal attack at room temperature of 26.2 deg C and relative humidity of 80% for 12 weeks. By the same method and under artificial weathering conditions at 48.9 - 1.1 deg C for 14 days, chlorinated coconut oil was leached out from the treated blocks at 0.01 lb/cu.ft. and found to be effective at threshold concentration of 0.11% or with retention of 0.0273 lb/cu.ft.