The invention relates to a thread forming tool having a thread part based on a helical effective surface (1), and an adjoining clamping shank (2), wherein the helical effective surface (1) is formed by pressing lobes (5) and the thread part extends from a chamfer or taper (6) in the direction of the clamping shank (2). Furthermore, at least one axially oriented, groove-like cooling channel (7) that runs between the pressing lobes (5) and extends from the chamfer or taper (6) to the clamping shank (2) is provided. According to the invention, the width of the at least one cooling channel (7) increases from the chamfer (6) in the direction of the clamping shank (2).