Structural elements in building and bridge construction may be subjected to the significantrnpure torsional moment that affects the design. As a result, in last century ,there is anrnenormous amount of knowledge that has been generated on the behavior, design andrndetailing of the reinforced concrete member. however, concrete cover spalling phenomenarndue to torsional moment is not adequately addressed. rnIn this study, Experimental investigation is conducted to study the effect of concrete coverrnon the behavior of reinforced concrete members subjected to pure torsion. Nine largernreinforced concrete beams in three experimental sets, with three different thickness ofrnconcrete cover were tested under pure torsional load. rnIn all the experimental program increasing the thickness of concrete cover for equivalentrnsectional properties decrease its torsional capacities. Beside relatively larger transversernreinforcement diameter, which is diameter 10mm increases its ultimate torsional capacityrnof the beams compared to that of equivalent area of transverse reinforcement diameterrndimeter 8mm in the experimental test conducted. rnIn the study, here also again, high strength concrete shows relateively small influence inrnits ultimate capacity of the member but it enhance the cracking capacity of the beam. rnSince, spalling of concrete cover is critical for pure torsional resistance, it also affect thernyield point of the transverse reinforcement. rnGenerally speaking , the thickness of concrete cover has huge impact on the ultimaternstrength as well as the overall behavior of reinforced concrete members.