A process for the gasification of biomass and/or coal with an at least partial carbon dioxide separation using a combined combustion/gasification reactor having a combustion part and a gasification part, comprising the steps of: a) feeding the coal and/or feeding biomass into the gasification part of the combustion/gasification reactor; b) in the gasification part, optionally under a feed of water or water vapour, heating and optionally pressuring the coal and/or the biomass at an elevated temperature and at an optionally elevated pressure in order to generate a product gas; c) filtering the product gas to separate ash, soot and other solid particles from the product gas; d) feeding the filtered product gas and an at least partially oxidized bed material into the combustion part of the combustion/gasification reactor, wherein the bed material is an oxygen transfer material, preferably selected from a group of bulk or supported materials containing Cu, Fe, Mn, Ni, Si, Al, Mg, Ca, Ti, La, Ce and/or Zr, their oxides, hydroxides, silicates, carbonates, sulphides or sulphates as well as any mixture thereof; e) in the combustion part, at least partially reducing the oxidized bed material by at least partially combusting the filtered product gas in order to generate heat that is being transferred partially into the gasification part; f) leading the exhaust gas of the combustion part into a further combustion reactor and leading the at least partially reduced bed material into an oxidation reactor fed with air in order to at least partially re-oxidize the bed material prior to its recirculation, wherein the bed material is used as sulphur transfer material by sulfidation during the at least partial reduction of the bed material in presence of the filtered product gas and subsequent oxidation of the bed material with inherent SO2-formation in the oxidation reactor; and wherein the freshly re-oxidized bed material is fed first into the further combustion reactor and subsequently into the combustion part as seen in the material flow direction of the bed material; and wherein the heat generated in the oxidation reactor and/or in the further combustion reactor is transferred to the gasification part by means of a suited heat transfer device such as heat pipes. a) feeding the coal and/or feeding biomass into the gasification part of the combustion/gasification reactor; b) in the gasification part, optionally under a feed of water or water vapour, heating and optionally pressuring the coal and/or the biomass at an elevated temperature and at an optionally elevated pressure in order to generate a product gas; c) filtering the product gas to separate ash, soot and other solid particles from the product gas; d) feeding the filtered product gas and an at least partially oxidized bed material into the combustion part of the combustion/gasification reactor, wherein the bed material is an oxygen transfer material, preferably selected from a group of bulk or supported materials containing Cu, Fe, Mn, Ni, Si, Al, Mg, Ca, Ti, La, Ce and/or Zr, their oxides, hydroxides, silicates, carbonates, sulphides or sulphates as well as any mixture thereof; e) in the combustion part, at least partially reducing the oxidized bed material by at least partially combusting the filtered product gas in order to generate heat that is being transferred partially into the gasification part; f) leading the exhaust gas of the combustion part into a further combustion reactor and leading the at least partially reduced bed material into an oxidation reactor fed with air in order to at least partially re-oxidize the bed material prior to its recirculation, wherein the bed material is used as sulphur transfer material by sulfidation during the at least partial reduction of the bed material in presence of the filtered product gas and subsequent oxidation of the bed material with inherent SO2-formation in the oxidation reactor; and wherein the freshly re-oxidized bed material is fed first into the further combustion reactor and subsequently into the combustion part as seen in the material flow direction of the bed material; and wherein the heat generated in the oxidation reactor and/or in the further combustion reactor is transferred to the gasification part by means of a suited heat transfer device such as heat pipes.