Water-in-diesel emulsion, also known as WIDE fuel, is one of the promising alternative fuels for diesel engines due to its positive impact on the performance and combustion characteristics of the engine, while at the same time reducing the emissions of NOx and particulate matter, without the need to modify the diesel engine. Cetane number is a key property that is considered in the formulation of diesel fuel. Cetane number is used to determine the ignition quality of fuel. One of the limitations in designing the diesel fuel formulation is the limited experimental data. The objective of this paper is to develop the cetane number property estimations for a pure compound. A property model was developed using the group contribution approach. In this approach, the molecular structure of the chemical was represented and divided into three levels, namely first-order (220 groups), second-order (130 groups), and third-order (74 groups). The cetane number with the group contribution occurrences of 271 chemicals were regressed using linear regression in MATLAB software to generate the contribution values of the three group levels. The regression step yielded contribution values of 43 groups for the first-order, 35 groups for the second-order, and 7 for the third-order. The coefficient of determination, R2, for the cetane number property models was 0.9447, indicating that the proposed model had a good correlation and is reliable to use.