There are several different classes of organic peroxides used in crosslinking HNBR. The most used are diakyl, alkyl-arakyl, and diaralkyl peroxides. These peroxides offer high activity and good scorch safety, but cure temperature can be somewhat of a limitation. These peroxides require cure temperatures in excess of 165°C or long cure times if below the optimum decomposition temperatures. While the alkyl peroxides are the most common they are not the only option. Peroxy ketales have been around for a long time but are not widely used. These peroxides offer advantages in applications where the cure temperature is below 165°C. The negative to these peroxides is that peroxy ketals are lower in activity and can be somewhat scorchy compared to the alkyl peroxides. Studies have been done looking at blends of alkyl-arakyl and peroxy ketal peroxides to optimize HNBR formulations for low temperature cures. However, these blends can also be advantageous for high temperature cures where fast cycle times are needed. In addition to the curing characteristics, how these blends impact long term aging performance are also discussed.