An improved high pressure turbine rotor blade and tip cap structure therefor is provided which comprises a tip end closure for the blade bonded to the end wall of the blade casting and including a base plate member and a pair of upstanding side walls defining a peripheral contour coincidental with and faired to the cambered side walls of the casting, the base plate member having a plurality of radially outwardly opening passageways therethrough and disposed along the chord of the blade and communicating with a channel included in the radially outwardly facing surface of the casting along a chord of the blade, the passageways disposed along axes at angles to the base plate whereby coolant fluid flowing therethrough is directed against the tip side wall surfaces; and opening is provided through the end wall of the casting in the form of a slit or a plurality of holes along the chord of the blade and intersecting the channel, to define an outlet through the end wall for passage of coolant fluid through the blade.