Reactive oxygen and nitrogen species (RONS) play an important role as signaling molecules in redox reactions throughout a plant life cycle. The purpose of this study was to assess how hydrogen peroxide (H2O2), a reactive oxygen species (ROS) and reactive nitrogen species (RNS) generated from sodium nitroprusside (SNP) and sodium nitrite, affects the germination, growth, and chemical contents of two rice cultivars (Pathum Tani and Sanpatong). The results showed that RNS generated from chemical donors and, especially, H2O2, enhanced the germination of the studied rice cultivars. Among the three chemical donors, H2O2 showed the best efficacy of the reactive species for activating early seed germination, followed by sodium nitrite and SNP. The highest percentage of seed germination rose to 99% at 6 h germination time after treatment with 25 mM of H2O2 for 24 h. Moreover, H2O2 produced a significant increase in the α-amylase activity and total soluble proteins. It was observed that a treatment with H2O2 on germinated seeds produced radicles with a dark blue color for longer than treatments with sodium nitrite and SNP. Our findings imply that H2O2 had a critical role in improving the germination and altering the chemical contents of rice seeds.