A process for catalytic gasification of carbonaceous feedstock to synthesis gas, said process comprising the following steps: i. gasifying a primary portion of said carbonaceous feedstock in a fluidized gasification zone (102, 202) at a temperature between 600-800 °C with steam and in the presence of a catalyst comprising an alkali metal compound impregnated on a solid particulate carrier, to produce the synthesis gas; wherein heat for the endothermic gasification reaction is supplied by said heated solid particulate carrier provided in said fluidized gasification zone at a catalyst to feedstock weight ratio of 2:1 to 50:1, wherein said alkali metal compound is selected from the group consisting of hydroxide, nitrate, and carbonate of K impregnated on said solid particulate carrier selected from γ-alumina, silica, ZSM-5, fluid catalytic cracking spent catalyst and mixtures thereof, by at least one method selected from physical mixing and wet impregnation, wherein, the ratio of said alkali metal compound to said solid particulate carrier is in the range of 1:1 to 1:10; ii. discharging heat-extracted solid particulate carrier impregnated with said alkali metal compound from an operative top of the fluidized gasification zone (102, 202) to a fluidized combustion zone (140, 240); and iii. combusting a secondary portion of said carbonaceous feedstock and unreacted carbon from said fluidized gasification zone (102, 202) in said fluidized combustion zone (140, 240) at a temperature between 800 - 840 °C with air, wherein heat generated during the exothermic combustion reaction is transferred to said heat-extracted solid particulate carrier to provide said heated solid particulate carrier which is re-circulated to said fluidized gasification zone (102, 202), wherein the alkali metal catalyst is potassium salt selected from potassium carbonate (K 2 CO 3), potassium hydroxide, and potassium nitrate (KNO 3). i. gasifying a primary portion of said carbonaceous feedstock in a fluidized gasification zone (102, 202) at a temperature between 600-800 °C with steam and in the presence of a catalyst comprising an alkali metal compound impregnated on a solid particulate carrier, to produce the synthesis gas; wherein heat for the endothermic gasification reaction is supplied by said heated solid particulate carrier provided in said fluidized gasification zone at a catalyst to feedstock weight ratio of 2:1 to 50:1, wherein said alkali metal compound is selected from the group consisting of hydroxide, nitrate, and carbonate of K impregnated on said solid particulate carrier selected from γ-alumina, silica, ZSM-5, fluid catalytic cracking spent catalyst and mixtures thereof, by at least one method selected from physical mixing and wet impregnation, wherein, the ratio of said alkali metal compound to said solid particulate carrier is in the range of 1:1 to 1:10; ii. discharging heat-extracted solid particulate carrier impregnated with said alkali metal compound from an operative top of the fluidized gasification zone (102, 202) to a fluidized combustion zone (140, 240); and iii. combusting a secondary portion of said carbonaceous feedstock and unreacted carbon from said fluidized gasification zone (102, 202) in said fluidized combustion zone (140, 240) at a temperature between 800 - 840 °C with air, wherein heat generated during the exothermic combustion reaction is transferred to said heat-extracted solid particulate carrier to provide said heated solid particulate carrier which is re-circulated to said fluidized gasification zone (102, 202), wherein the alkali metal catalyst is potassium salt selected from potassium carbonate (K 2 CO 3), potassium hydroxide, and potassium nitrate (KNO 3).