Cement, a substance manufactured industrially, produces 0.9 pounds of carbon dioxide for every pound produced, and concrete, the most popular construction material, typically contains 15 cement. Cement is the primary component of concrete used as a binder, and its use is hard to regulate in the face of expanding worldwide demand. Literature suggests that using supplemental cementitious materials is the most practical approach to lowering concrete�s cement content. Volcanic pumice powder ash is one such substance found in nature (VPPA). It has important properties for use as a supplemental cementitious material. The material has been used in previous experiments, with varying results, making it difficult to reliably assess its influence on mechanical qualities. The reason for this research is because sophisticated methods of assessment, such as Response Surface Methodology, have not been used before on VPPA-modified concrete (RSM). The study aimed to determine the effect of VPPA on Compressive Strength (CS), Flexural Strength (FS), Splitting Tensile Strength (STS) and Modulus of Elasticity (MOE) of cement concrete. For this purpose, VPPA was added in concrete at 3, 6, 9, 12, 15 and 18 and experiments were performed for each sample at 7, 14 and 28 days. Results from the experimental analysis indicated positive outcomes for all mechanical properties (CS, FS, STS and MOE). However, the VPPA was found feasible for concrete mechanical property improvement up to 12, after which the negative impact was observed on all mechanical properties. RSM was then applied to develop the model for VPPA addition in concrete. R-Square and Adeq precision values indicated highly significant results, and four equations were developed for predicting CS, FS, STS and MOE. Further, optimization was also performed on the RSM findings to determine the model�s effectiveness. Experiments were conducted following the optimization results to determine the practicality of optimized model. Less than 5 error was found between the theoretically optimized values and experimental values of CS, FS, STS and MOE. © 2023, The Author(s), under exclusive licence to Springer Nature Switzerland AG.