As we consider the pollutions caused by combustion engines, they have a big impact on several problems like global warming, acid rain, etc. Engineers and scientists are willing to control the pollutants and to reduce them as low as possible. There are some possible solutions to reduce environmental problems such as diesel particulate filters, high pressure fuel injection equipment, and sophisticated piezo injectors and associated control systems. However, all mentioned solutions need a modification on the current engine system to be used. Because of high costs of modification, recently, fuel-based solutions are more popular. This study investigates one of the possible fuel-based solutions which is water-in-diesel emulsions. Through the work, spray characteristics such as spray penetration and spray angle have been examined and compared with neat diesel spray. In order to achieve the purpose of this research, experiments have been carried out in a constant volume combustion chamber and all have been recorded by the help of a high-speed camera. A Matlab algorithm has been developed to analyse the recorded data. It was found that, due to lower volatility of the water, water-in-diesel emulsion has longer and wider spray when compared to neat diesel spray. According to the literature, this results in better fuel-air mixing for combustion process, hence cleaner exhaust gas.