A membrane-less reactor for conversion of carbon dioxide to alcohols by microbial electrosynthesis, wherein the membrane-less reactor comprises: a) a tubular gas diffusion electrode with an active layer modified with an electroactive material as a working electrode; b) a circular counter electrode, which is a disc-shaped mesh having a central cavity; c) a porous bio-electroactive filter, which is arranged in association with the active layer of the tubular gas diffusion electrode to develop an electro-active biofilm, comprising a biocatalyst for the microbial electrosynthesis; d) an electrolyte; and e) samplings ports; wherein the working electrode and the circular counter electrode are positioned perpendicular to each other to avoid oxygen contact at the gas diffusion electrode and the working electrode is vertically arranged inside the reactor such that it remains completely immersed in the electrolyte with the active layer facing towards the electrolyte and gas diffusion layer facing towards inner side of cylinder without contacting the electrolyte to form a gas compartment towards the inner core of the tubular electrode, and wherein the counter electrode is positioned on top of the electrolyte; wherein the reactor is single chambered and can be operated in batch or continuous or semi-continuous mode in a continuous stirred tank reactor or in a sequential batch reactor. a) a tubular gas diffusion electrode with an active layer modified with an electroactive material as a working electrode; b) a circular counter electrode, which is a disc-shaped mesh having a central cavity; c) a porous bio-electroactive filter, which is arranged in association with the active layer of the tubular gas diffusion electrode to develop an electro-active biofilm, comprising a biocatalyst for the microbial electrosynthesis; d) an electrolyte; and e) samplings ports; wherein the working electrode and the circular counter electrode are positioned perpendicular to each other to avoid oxygen contact at the gas diffusion electrode and the working electrode is vertically arranged inside the reactor such that it remains completely immersed in the electrolyte with the active layer facing towards the electrolyte and gas diffusion layer facing towards inner side of cylinder without contacting the electrolyte to form a gas compartment towards the inner core of the tubular electrode, and wherein the counter electrode is positioned on top of the electrolyte; wherein the reactor is single chambered and can be operated in batch or continuous or semi-continuous mode in a continuous stirred tank reactor or in a sequential batch reactor. wherein the working electrode and the circular counter electrode are positioned perpendicular to each other to avoid oxygen contact at the gas diffusion electrode and the working electrode is vertically arranged inside the reactor such that it remains completely immersed in the electrolyte with the active layer facing towards the electrolyte and gas diffusion layer facing towards inner side of cylinder without contacting the electrolyte to form a gas compartment towards the inner core of the tubular electrode, and wherein the counter electrode is positioned on top of the electrolyte; wherein the reactor is single chambered and can be operated in batch or continuous or semi-continuous mode in a continuous stirred tank reactor or in a sequential batch reactor.