Composite materials utilizing natural fibers are becoming more popular and have a broad range of usage in the industry. Natural fibers come from nature and they have many advantages which are low cost, easily available and environmentally friendly. Some natural fibers are obtained from plants while others could be obtained from trees. Commonly used natural fibers are jute, flax, sisal, bamboo and ramie. In order to produce composite materials from natural fibers, both thermoset and thermoplastic resins can be used. In this experimental study, epoxy resin was combined with jute and flax woven fibers to obtain hybrid composites. Firstly, fibers were treated with a solution containing 5 % alkaline to improve the mechanical properties of the fibers. Two different chemicals were used to improve the fire resistance of the fibers namely ammonium sulfate and diammonium phosphate. Two different solutions were prepared for this purpose; a solution containing 20% of ammonium sulfate was prepared for the treatment of jute fiber and another solution containing 10% of diammonium phosphate was prepared for the treatment of flax fiber. The epoxy was applied to both samples by hand layup method and the curing was carried out by using the hot press. The hardness, thickness and mass of the produced samples were measured and a fire experiment was carried out. Several parameters such as flammability, heat distribution and temperature of the sample surfaces were investigated. Low flammability, low heat distribution and low temperature properties were observed on the surfaces of the samples which were chemically treated by using ammonium sulfate and diammonium phosphate.