Priming is considered a promising technique to speed up germination and to improve seed performance under unfavorable conditions. The effects of incorporating Prohexadione-Calcium (Pro-Ca) into priming solutions on low temperature germination and emergence performances of sweet pepper seeds were investigated. Seeds were primed in 3% KNO3, 2% KH2PO4, and 10% PEG solutions containing 0, 25, 50, and 100 mg.L-1Pro-Ca in darkness at 25°C for three days. The total number of treatments was 12. After priming treatment, the seeds were washed with distilled water and dried at 20°C on filter paper for 24 h, and then subjected to germination and emergence tests at 15°Cingrowth chamber. Priming pepper seeds in the presence or absence of plant growth regulators improved final germination percentage (FGP), mean time to germination time (MTG), and germination index (GI), final emergence percentage (FEP), and mean time to emergence (MTE) compared to nonprimed seeds. Priming seeds in KH2PO4 solution containing 25 mg.L-1 Pro-Ca resulted in the highest FGP (85.33%), and the lowest MTG (12.83 days) at 15°C. The highest FEP (95%) was obtained from the application of KNO3 + 50 mg.L-1 Pro-Ca treatment. Final emergence percentage was 64% in nonprimed seeds. The improvements by Pro-Ca might be related to the alterations of some ingredients of seeds, such as proline content, total carbohydrates and total soluble sugars. The results indicated that inclusion of Pro-Ca into the priming solutions can be used as an effective method to improve performance of sweet pepper seeds at low temperature.