Methanol has a strong potential to be used as a substitution for fossil fuel due to its several advantages such as the enthalpy of evaporation, high octane numbers and high oxygen content. However, unlike the non-polar gasoline, it is polar and very miscible with water and this leads to the phase separation of the gasoline-methanol blend. Therefore, this study was conducted to understand the role of ethanol in improving the homogeneity and stability of the gasoline-methanol blend. Molecular analysis was conducted through the HyperChem software to simulate important molecular properties of each constituent substance. Isooctane as a single substance was chosen to represent multi-substance gasoline to simplify the analysis of molecular interactions. Experimental tests were also conducted by mixing several fractions of the isooctane-methanol blend, and the ethanol was dripped gradually into separate phases of the mixture. The manual stirring was conducted, then allowed to stay for 120 s on each drop. Visual observation and addition of ethanol drops were stopped after the mixture separation phase did not occur. The results showed a certain amount of ethanol (up to 22%) was needed to improve the homogeneity and stability of the isooctane- methanol blend. The ethanol fractions up to 22% v/v needs to be added to block hydrogen bonds between the methanol-water molecules. The addition of ethanol produces new hydrogen bonds that were stronger than the methanol and water bond to improve the homogeneity and stability of the isooctane-methanol blend.