In this experimental research work, we explored the efficiency of external reinforcements, made of carbon fiber composite materials CFRP on high slender reinforced concrete columns. A particular attention has been paid to the reduction of the instability risk of the existing slender columns, using various arrangements of CFRP strengthening. The behavior under monotonic cyclic compression loads, has been explored on 7 reinforced concrete columns, having a very high geometric slenderness equivalent to l/a=29. Experimental responses allowed us, the idealization of the global behavior by elastic perfectly-plastic simplified models, the highlighting and evaluation of the stiffness variation according to the load, to note the changes on the columns deformability, to measure energy characteristics induced by the different provisions of reinforcements. As interesting observation, we cite the positive effect in terms of bearing capacity and deformability on all of the reinforced columns.