Biodiesel, a widely recognized renewable fuel, encounters challenges such as elevated viscosity and low volatility, which can negatively impact engine efficiency. In this research, a biodiesel-butanol blend was formulated by incorporating butanol into biodiesel. A high-pressure common rail injection system was employed to capture the spray characteristics of both pure biodiesel and its butanol blends counterpart using high-speed imaging. The radial diffusion characteristics spray were examined and systematically evaluated. Additionally, the overall radial dispersion capability was investigated by determining the average spray width and cone angle, derived from the maximum width. The gas entrainment region was also considered in the analysis. Findings indicate that the introduction of butanol improved both the peak and mean radial dispersion of biodiesel spray.