A turbine airfoil comprising: - a leading edge and a trailing edge, the trailing edge being located axially downstream from the leading edge according to a flow direction F that corresponds to the direction of external hot flow when flowing outside the airfoil in operating mode; - a suction side wall and a pressure side wall both extending axially between the leading edge and the trailing edge, the suction side wall being spaced from the pressure side wall and defining between them a central cavity of the airfoil, the central cavity being configured to allow the passage of cooling flow inside the airfoil; the airfoil being characterised by further comprising - a row of a plurality of triangular pedestals being arranged at least partially between the suction side wall and the pressure side wall at the trailing edge; and - at least one diffusing duct provided between each two consecutive pedestals, wherein the central cavity comprises a height decreasing in the flow direction F; the triangular pedestals comprise a wide side (6.3) faced to the leading edge and two lateral walls (6.2) joining in a vertex (6.1) that is opposite to the wide side (6.3) and faced to the trailing edge so that at least one diffusing duct is provided between two lateral walls (6.2) from two consecutive triangular pedestals, and each diffusing duct comprises • a restrictor configured for allowing the penetration of the cooling flow flowing within the central cavity into the diffusing duct, and • a slot configured for allowing the exit of the cooling flow flowing through diffusing ducts over the trailing edge, this slot being common for all the diffusing ducts since each slot from a diffusing duct merges with the rest of slots from the other diffusing ducts, and this common slot being a diffuser exit area of cooling flow, the slot from each diffusing duct being provided between the vertexes (6.1) opposite to the wide sides (6.3) of the triangular pedestals from consecutive triangular pedestals. - a leading edge and a trailing edge, the trailing edge being located axially downstream from the leading edge according to a flow direction F that corresponds to the direction of external hot flow when flowing outside the airfoil in operating mode; - a suction side wall and a pressure side wall both extending axially between the leading edge and the trailing edge, the suction side wall being spaced from the pressure side wall and defining between them a central cavity of the airfoil, the central cavity being configured to allow the passage of cooling flow inside the airfoil; the airfoil being characterised by further comprising - a row of a plurality of triangular pedestals being arranged at least partially between the suction side wall and the pressure side wall at the trailing edge; and - at least one diffusing duct provided between each two consecutive pedestals, • a restrictor configured for allowing the penetration of the cooling flow flowing within the central cavity into the diffusing duct, and • a slot configured for allowing the exit of the cooling flow flowing through diffusing ducts over the trailing edge, this slot being common for all the diffusing ducts since each slot from a diffusing duct merges with the rest of slots from the other diffusing ducts, and this common slot being a diffuser exit area of cooling flow, the slot from each diffusing duct being provided between the vertexes (6.1) opposite to the wide sides (6.3) of the triangular pedestals from consecutive triangular pedestals.