Two cultivars of seeds from the National Corn and Sorghum Research Center (NCSRC) and a Private Company (PC) were hydroprimed for 3 to 12 h, then artificially aged at 42°C, 100% RH for 96 h. The germination of NCSRC unprimed seeds after accelerated aging was greater than the PC seeds caused by its initial ascorbate peroxidase (APX) activity. Hydropriming for 3 to 9 h prevented any loss in germination due to the aging process. However, this effect was inhibited by hydropriming for a longer duration. The amelioration of the aging process may be due to a reduction in oxidative stress by antioxidant enzymes. Superoxide dismutase (SOD) and APX may play a role in NCSRC, but APX only contributed in PC seeds. The high amylase activity with remaining glucose content may associate to improve germination in the hydroprimed with aged seeds. Hydropriming periods of greater than 9 h resulted in loss of seed germination after accelerated aging. This result was caused by a reduction in sucrose and raffinose content. The sharply increased amylase activity for both cultivars and the decreased activities of SOD and APX in NCSRC and APX in PC may also indicate the loss of primed seed vigor. © 2012 Academic Journals.