Burner for air-gas mixtures which comprises: - a gas combustion head, which comprises: a main body delimiting an internal distribution chamber, connected to at least one feed duct for introducing a fuel gas - air mixture inside said internal distribution chamber, - a combustion chamber, to which said combustion head is coupled, and which is provided with: - a bottom wall facing said distribution wall and susceptible of reversing by 180 degrees the advancing direction of the burnt gases of said air/gas mixture, - an opposite base wall on which said combustion head is provided, and toward which said burnt gases are susceptible of being directed by said bottom wall; at such base wall exhaust sections for the burnt gases being obtained, outside said distribution wall; characterized in that the main body is provided with at least one distribution wall, having a plurality of openings, through which the fuel gas - air mixture flows from said internal distribution chamber of said main body, to a combustion area outside said main body; the distribution wall of said main body of said combustion head has conical form with sections substantially circular with respect to planes orthogonal to the central axis of the cone and with convexity directed towards said internal distribution chamber; said distribution wall being formed by two sheet-shaped plates with said plurality of openings obtained in their thickness, such openings have size substantially equal to each other, and are arranged such that they are susceptible of being traversed, orthogonally to the conical surface of said sheet-like plates in directions tilted towards the central axis of said cone, by flows of said air-gas mixture with substantially equal flow speeds generating flames inside said combustion area that are substantially equal and symmetrically arranged around the central axis of said cone, converging towards such central axis and susceptible of forming together a flow of hot burnt gases with maximum flow rate at said central axis; wherein said two conical plates are each provided with a plurality of openings, parallel and spaced from each other along the extension of the longitudinal axis of said combustion chamber coinciding with the central axis of the cone of said combustion head; wherein the two conical plates of said conical distribution wall are placed between said internal distribution chamber and said combustion area; wherein said combustion chamber is provided with axial symmetry centered on the axis of the cone of said combustion head. - a gas combustion head, which comprises: a main body delimiting an internal distribution chamber, connected to at least one feed duct for introducing a fuel gas - air mixture inside said internal distribution chamber, - a combustion chamber, to which said combustion head is coupled, and which is provided with: - a bottom wall facing said distribution wall and susceptible of reversing by 180 degrees the advancing direction of the burnt gases of said air/gas mixture, - an opposite base wall on which said combustion head is provided, and toward which said burnt gases are susceptible of being directed by said bottom wall; at such base wall exhaust sections for the burnt gases being obtained, outside said distribution wall; a main body delimiting an internal distribution chamber, connected to at least one feed duct for introducing a fuel gas - air mixture inside said internal distribution chamber, - a combustion chamber, to which said combustion head is coupled, and which is provided with: - a bottom wall facing said distribution wall and susceptible of reversing by 180 degrees the advancing direction of the burnt gases of said air/gas mixture, - an opposite base wall on which said combustion head is provided, and toward which said burnt gases are susceptible of being directed by said bottom wall; at such base wall exhaust sections for the burnt gases being obtained, outside said distribution wall; - a bottom wall facing said distribution wall and susceptible of reversing by 180 degrees the advancing direction of the burnt gases of said air/gas mixture, - an opposite base wall on which said combustion head is provided, and toward which said burnt gases are susceptible of being directed by said bottom wall; at such base wall exhaust sections for the burnt gases being obtained, outside said distribution wall;