Vertical axis wind turbine, which comprises: - a central rotation shaft having a vertical axis; - two or more blades, each of which provided with wing profile and with an elongated length that is substantially extended as an arc with concavity directed towards said central rotation shaft, from a lower end to an upper end, at which said blade is mechanically coupled to said central rotation shaft in order to transmit a rotation motion around the aforesaid vertical axis; wherein the wing profile of each said blade is marked by: - a progression of its chord (c) as a function of the height (h) of the wing profile of said blade having: - two first minimum chord values (c min1, c min2) respectively at the aforesaid upper and lower ends (h max, h min) of the height of said blade; - a second minimum chord value (c min3) at a median value (h med) of the height of said blade and - and a first and a second maximum chord value (c max1, c max2) respectively at two intermediate heights (h int1 and h int2) of the wing profile of said blade interposed between the median value (h med) of the height of said blade and the heights (h min, h max) of the aforesaid lower and upper ends of said blade, respectively; the wing profile being characterised by: - a progression of the ratio (s/c) between its thickness (s) and its chord (c) as a function of the height (h) of the wing profile of said blade having: - a first and a second minimum ratio value ((s/c) min1; (s/c) min2) respectively at the aforesaid lower and upper ends (h min, h max) of the height of said blade; - a maximum ratio value ((s/c) max) at a median value (h med) of the height of said blade. - a central rotation shaft having a vertical axis; - two or more blades, each of which provided with wing profile and with an elongated length that is substantially extended as an arc with concavity directed towards said central rotation shaft, from a lower end to an upper end, at which said blade is mechanically coupled to said central rotation shaft in order to transmit a rotation motion around the aforesaid vertical axis; - a progression of its chord (c) as a function of the height (h) of the wing profile of said blade having: - two first minimum chord values (c min1, c min2) respectively at the aforesaid upper and lower ends (h max, h min) of the height of said blade; - a second minimum chord value (c min3) at a median value (h med) of the height of said blade and - and a first and a second maximum chord value (c max1, c max2) respectively at two intermediate heights (h int1 and h int2) of the wing profile of said blade interposed between the median value (h med) of the height of said blade and the heights (h min, h max) of the aforesaid lower and upper ends of said blade, respectively; the wing profile being characterised by: - two first minimum chord values (c min1, c min2) respectively at the aforesaid upper and lower ends (h max, h min) of the height of said blade; - a second minimum chord value (c min3) at a median value (h med) of the height of said blade and - and a first and a second maximum chord value (c max1, c max2) respectively at two intermediate heights (h int1 and h int2) of the wing profile of said blade interposed between the median value (h med) of the height of said blade and the heights (h min, h max) of the aforesaid lower and upper ends of said blade, respectively; the wing profile being characterised by: - a progression of the ratio (s/c) between its thickness (s) and its chord (c) as a function of the height (h) of the wing profile of said blade having: - a first and a second minimum ratio value ((s/c) min1; (s/c) min2) respectively at the aforesaid lower and upper ends (h min, h max) of the height of said blade; - a maximum ratio value ((s/c) max) at a median value (h med) of the height of said blade. - a first and a second minimum ratio value ((s/c) min1; (s/c) min2) respectively at the aforesaid lower and upper ends (h min, h max) of the height of said blade; - a maximum ratio value ((s/c) max) at a median value (h med) of the height of said blade.