Sodium silicate and sodium borate were tested as 6ame retardants on two types of paper sheet (100% rice straw pulp paper with a high silica content while the other consisted of 100% wood pulp paper). After addition of inorganic 6ame retardant salts (sodium silicate and sodium borate) on to the two samples of paper, the thermal behaviour of the treated paper sheets revealed di4erences in the course of the di4erential thermal analysis curves. The thermal analysis studies were carried out under an oxidizing atmosphere using di4erential thermal (DTA) and thermogravimetric (TGA) analysis. The 6ame retardants used in this study reduced the amount of volatile products formed during decomposition of the paper and increased the weight loss due to formation of char for the treated papers. The thermal degradation of paper can be considered as a 5rst order degradation. Two stages of thermal degradation were kinetically di4erentiated, namely, a volatilization stage and a decarbonization stage. The activation energy for these two stages were calculated. The addition of 6ame-retarding salts decreased the activation energy for both stages. Sodium silicate salt showed more reduction of activation energy than sodium borate, especially for the rice straw paper.