In this study the treated and untreated kenaf fiber mat (KFM) reinforced unsaturated polyester composites were prepared and hybridization of two types of natural fibres reinforced unsaturated polyester (UPE) composites was fabricated. Hybrid composites of KFM and wood sawdust (WS) were created by lay-up technique and continue with compression moulding. The KFM was retted enzymatically, washed, dried and combed with a nylon brush. The KFM was treated with two type of chemical treatment to composite fabrication. There were alkaline treatment and peroxide treatment. Untreated KFM was also used to prepare the composites to serve as control. After chemical treatment, the treated and untreated KFM undergo Fourier Transform Infrared Spectroscopy (FTIR) process and continues to composite fabrication with the fixed material composition. Finish composites were subjected to mechanical test which was flexural test and water absorption test. The results obtained indicated an increase in all the parameters tested with the fiber treatment. This is because during the chemical treatment, the lignin, hemi-celluloses, pectin and other impurities had removed. This shows that, the enhancement of the natural cellulosic fibers to different composite applications can be achieved via fibre chemical treatments. From water absorption process, the thickness swelling of each composite measured and the result had was shown that the higher water absorption the bigger the thickness swelling.