Seed dormancy of oil palms, after harvesting with low and non-uniform germination, is a significant problem for commercial seedling production. Practically, dry-heat treatments are performed to release the dormancy. This study is aimed to investigate the optimum heating requirement to remove the Sub-PSU1 oil palm seed dormancy, after different storage times while waiting for a commercial order and breeding program before the germination occurs. Abscisic acid levels, after the heat treatment of stored seeds were also studied concurrently. It was found that the dormancy of oil palm seeds had entirely declined naturally after 15 months of storage at 20°C, with germination of 85% within 49 days. A dry heat treatment at 40°C for 45 days, being shorter than the traditional practice (60-80 days), is found influential in promoting the germination of oil palm seeds after 15 months of storage. This treatment also effectively delayed the accumulated abscisic acid in stored seeds at higher levels, with a more extended storage period. In conclusion, the specific condition of the dry heat treatment for breaking the seed dormancy during long-term storage at a low temperature (20°C), will certainly benefit commercial seedling production, when used in the breeding programmes of sub-PSU1 oil palm.