A multizones modeling of the combustion characteristics of the spark assisted homogeneous charge compression ignition (HCCI) engine is performed. The main aim of this work is to deduce the simulation to reveal the in-cylinder conditions prevailing during the spark assisted HCCI combustion which is difficult to obtain experimentally. Conditions such as in-cylinder burned gas temperature, NOx formation, and mean in-cylinder charge temperature and pressure conditions. The second aim of the present work is the mapping of the influence of NO doping on the incylinder conditions. Recent experimental studies have shown that NO has significant impact on hydrocarbon autoignition and the NO formed inside the burned gas can be used for autoignition control of HCCI engine combustion. The tuning of a zero-dimensional multizones phenomenological model is performed separately using experimental data for SI and HCCI operation keeping the same engine parameters, engine speed and air-fuel ratio to maintain simulation similarity. Variation of the burned gas temperatures inside the individual zones due to recompression effects and the formation of NOx inside these zones in a single engine stroke for different engine speed conditions are investigated. The mean unburned gas temperature and pressure conditions before the start of ignition are obtained for different operating conditions. The effect of NO on in-cylinder conditions is done by doping it in the order of one magnitude up.