BACKGROUND: For the first time, green coconut shell extract (GCSE) has been employed along with boric acid (BA) as a novel fire retardant agent to be applied to cellulosic paper. Green coconut shell extract can be considered a condensed phase based flame retardant agent as it contains silicate, other metals like potassium, zinc, copper and magnesium in the form of metallic salts, oxides etc. When GCSE was applied on paper, combine synergistic action of all these metal salts and oxides catalyze dehydration of the treated paper and also increased char formation. RESULTS: The treated papers were evaluated for their flame retardant properties by measurement of the limiting oxygen index (L01) and vertical flammability. A GCSE and 2% BA application was found to enhance the oxygen required for burning the paper as it showed an 101 value of 42 and also reduced its burning rate by promoting more dehydration and char formation. The thermal degradation and pyrolysis mechanisms were studied using thermo-gravimetric analysis (TGA). The imparting of a flame resisting property to a paper by use of the GCSE and BA, along with its charring behaviour, is discussed and the mechanisms operating postulated. CONCLUSION: As GCSE is a wastage product and available abundantly in India, making fire retardant cellulosic material by using GCSE is an attractive proposition (C) 2016 Society of Chemical Industry