An experimental investigation assessed the effects of Graphene Oxide (GO) at 25, 50, and 75 ppm on engine parameters in an HCCI engine operating with Algae Methyl Ester (AME) blends of 20, 40, and 60%. Homogeneous-Charge Compression Ignition (HCCI) diesel engine analysis and Response Surface Methodology (RSM) optimization were performed. GO additives improved engine performance and reduced emissions. Predicted and actual results showed lower BTE at 20.25% and higher BTE at 26%, lower BSFC at 1.69 kg/kWh and higher BSFC at 2.46 kg/kWh, lower CO at 0.04 vol% and higher CO at 0.22 vol%, lower HC at 18.82 ppm and higher HC at 30.3 ppm, lower NOx at 201 ppm and higher NOx at 301 ppm, and smoke reduction at 21.01% vs 35.4%. RSM model effectively predicts HCCI engine performance. © 2024 Elsevier B.V., All rights reserved.