One way to better protect combustible materials against initiating fires is the use of flame retardants. Every day we come across new innovations particularly in the areas of flame retardant fibres and chemicals. This study investigates fire retardancy effect of boron on two cotton fabrics. Boron can soluble in water, colourless and capable of melting by heat. Boron is highly resistant to fire due to the melting temperature of 2300 degrees C. Because of this property, it is used as a flame-retardant material. The objective of this study was to examine the feasibility of imparting flame-retarding functions to different textile materials through the application of boric acid with impregnation methods. Different concentrations of boric acid nanoparticles were examined to optimize the flame-retarding functions. Eventually, 45 degrees inclined combustion test are applied to the samples and examined the changes in strength of the samples. In this research; the aim is to bring in flame-retarding functions to different fabrics.