The effect of hydrogen peroxide (H 2 O 2 ) on premixed isooctane/air combustion was numerically investigated using detailed chemical kinetics (Peters’ mechanism) via CHEMKIN. Two cases were examined: one-dimensional, planar, adiabatic, premixed flame, which is of fundamental importance to many combustion systems including internal combustion engines, and zero-dimension, adiabatic Homogeneous Charge Compression Ignition (HCCI). Initial conditions investigated were at 298 K and 1 atm for the premixed flame and 343 K and 1 atm for the HCCI. The effects of H 2 O 2 addition on combustion characteristics including burning velocity, flame temperature, species concentration and ignition delay were deduced. Hydrogen peroxide was utilized as a possible means of emissions reduction. Specifically, the potential of CO reduction due to increased intermediate OH species was studied. The utilization of H 2 O 2 as a means of controlling ignition timing was also explored.