The present work describes application of mixture of Ammonium Sulfamate (AS) and Sodium Stannate (SS) on 100% cotton woven fabric for imparting eco-friendly Fire-Retardant (FR) finish without any harmful effect investigating fire retardant properties with respect to Limiting Oxygen Index (LOI), physical characteristics, inclined plan flammability test etc. The aim of the present work was to obtain LOI value around 30 or above with minimum char length and minimum loss of fabric tenacity. The treatment was carried out by impregnation of AS followed by SS in an aqueous solution and then drying at 1100C for 5 min and curing at 1500C for 4 min. After preliminary study with different concentrations (keeping total added chemical around 20%-24%) for AS and SS, final results indicated that 16% AS + 8% SS in combination renders LOI 38.30 and char length- 6.7 cm and around 30% loss of fabric tenacity. Preliminary investigation has also confirmed that 16% AS + 8% SS combination shows a synergistic effect as LOI value obtained by this chemical combination (16% AS + 8% SS) is higher than LOI value obtained by same % of application of AS or SS alone. Characterization of FR treated cotton was done by surface topography by SEM, functional groups by analysis of FTIR, element identification by XPS etc. Analysis of thermal behaviour by TGA confirms that after said FR treatment the residual char formation has increased by almost 25% and decomposition temperature of cellulose has been lowered considerably indicating a good fire-retardant property.