The motivation for the current work emanates from the conceptualization to improve the performance and emission characteristics of diesel engine fueled with biodiesel, by altering the fuel properties of it through the addition of additives. As such, 1,4-Dioxane, a multipurpose additive, has been zeroed in as one of the indispensible additive to be added with the optimum blend of KME (kapok methyl ester), a biodiesel produced from under-utilized kapok oil, with diesel to improve the engine characteristics. In the current work, 1,4-Dioxane was added with the optimum blend, B25 (25% KME and 75% diesel), in various proportions such as B25-5 ml (B25 - 99.5% and 1,4-Dioxane - 0.5%) and B25-10 ml (B25 - 99.0% and 1,4-Dioxane - 1.0%). With the addition of 1,4-Dioxane, the physical and thermal properties of B25 were improved, in particular the cold flow and ignition properties. As an outcome of the experimental investigation, BTE (brake thermal efficiency) was improved by 5.7% for B25-10 ml than B25 at full load condition. Correspondingly, the emissions such as HC (hydrocarbon), CO (carbon monoxide), NOx (oxides of nitrogen) and smoke were reduced by 25.3%, 22.5%, 15.2% and 24.6%, respectively, for B25-10 ml than B25. Interestingly, all the reported emissions for B25 with additive were much lower than diesel fuel, making it as one of the appropriate fuel blend for diesel engine in the near future. (C) 2014 Elsevier Ltd. All rights reserved.