An experimental study was performed to assess the combustion characteristics of iso-octane (a gasoline surrogate) at compression-ignition (CI) conditions. The fuel was injected into a quiescent-steady environment inside an optically accessible constant-volume combustion chamber with a 22.8 kg/m(3) ambient gas density and a 21 vol % O-2 concentration. Optical techniques including natural flame luminosity, OH-chemiluminescence, and shadowgraph imaging were performed to compare the combustion characteristics over ambient gas temperatures from 1000 to 1120 K. Measurements were also performed for n-heptane (a diesel surrogate) for reference purposes. Formaldehyde (CH2O) planar laser-induced fluorescence (PLIF) imaging was performed to confirm the presence of low-temperature reactions across the jet head, prior to the high-temperature ignition of iso-octane. From the measurement results, the lift-off lengths (LOLs), ignition delays (IDs), and their corresponding uncertainties for both fuels are observed to increase with lowering ambient temperature conditions. The LOLs, IDs, and their uncertainties for the iso-octane flames are also consistently measured to be higher than that of n-heptane, across the tested ambient temperature range. The results reveal that the highest variability detected for the flame stabilization distance of the iso-octane flame at the lowest tested ambient temperature condition (i.e., 1000 K) is attributable to the long transient stabilization phase that it exhibits after ignition. Additional tests performed using a single-injection test case with lower octane number fuel, as well as split-injection strategies with neat iso-octane as fuel, demonstrate their potentials to reduce the transient stabilization phase of the test flames when compared with those using a single-injection test case with neat iso-octane as fuel.