The aim of this study is to propose and test a new method for detection of oil spills in the world oceans using Sea-viewing wide Field-of-Wiew Sensor (SeaWiFS) imagery embedded in SeaStar satellite. The colour masking technique is proposed to extract the maximum oil spill pixels from the SeaStar/SeaWiFS satellite images by using fusion by arithmetic combination of the spectral bands method. Each image used is converted from RGB (red, green, blue) to HSI (hue, saturation, intensity) system. The resulting oil slicks are obtained visually in the intensity and saturation images. Then, the values of intensity and saturation are analysed to be potentially applied in other images. In this research, we applied our detecting oil spills algorithm in six different scenes, including different regions of the world oceans, and different dates. Finally, to validate our results, the method has been tested by using the oil spill pixel reference ratio. We found that the method can be used to support the detection of oil slicks, in spite of some limitations.