Due to stricter emission norms, diesel engine is facing challenges of in-cylinder emissions reduction. Low complexity emissions prediction models are desired, with a long term objective to extend it to emissions prediction during transient operations. This paper is focused on the formulation and investigation of simplified model for prediction of in-cylinder pressures, temperatures engine-out NOx and Soot emissions. Being a predictive model, this does not require cylinder pressure as an input. To have better computational efficiency, a single-zone model is used for the combustion model. Fuel burning rate is predicted using Watson model. Two-zone model has been formulated to predict NOx and Soot emissions. Flame temperatures are predicted by enthalpy balance. Thermal NO concentration is predicted by using Zeldovich mechanism. Soot prediction is based on approach proposed by Hiroyasu. Prediction model is validated using a Turbocharged DI Diesel engine, at various speed-load conditions. The predicted results of the in-cylinder pressure histories, NOx emissions and Soot emissions are in good agreement with the measured data.