The continuous and increasing in volume of fossil fuels utilization leads to an alarming increase in green-house gases emissions. Consequentially, the release of toxic agents may cause detrimental health issues and aggravate global warming effects. Biofuels, due to its reduced emission effects, are found to be a potential alternate to fossil fuels, especially for their usage in internal combustion engines under certain loading conditions. The present research work aims at investigating the effects of butanol blending ratio at different biogas flow rates on the performance and emission characteristics of a single-cylinder CI (Compression ignition) engine under Homogenous Charge Compression Ignition (HCCI) mode. Flow rates of biogas taken in the present study are 12 lpm and 16 lpm whereas the butanol is blended in biodiesel-DEE (Diethyl-ether) mixture at 10, 20 & 30% concentration by volume. The engine parameters analysed in the present work are brake thermal efficiency, Brake Specific Energy Consumption (BSEC), Hydrocarbons (HC), Carbon monoxide (CO), Oxides of Nitrogen (NOx) and Smoke emissions. Results showed that the butanol addition in the fuel reduced the NOx emissions considerably at various loads between 0.1 N-m to 15 N-m. Further increase in load resulted in knocking conditions in the engine due to multipoint ignition. Based on the experiments, it is witnessed that 30% of butanol blend in biodiesel-DEE mixture high efficiency and low smoke emissions compared to all other blends. Simultaneous reduction of NOx and smoke emissions is observed in HCCI mode. © Published under licence by IOP Publishing Ltd.