Application of high temperature superconductor Bi2Sr 2Ca2Cu3Ox (Bi-2223) compound embedded in an Ag matrix requires the knowledge of critical current as a function of mechanical properties. Commercial tapes available in different types have been developed in industrial production scale in which a combination of small diameter filaments, long tape lengths and a ductile matrix results in a conductor with low crack formation and good tolerance against strain. The measurement of critical current and the evaluation of n-index from V-I characteristic curves of Bi-2223/Ag composite tapes subjected to an initial bending strain as a function of number of thermal cycles were done for two types of Bi-2223/Ag composite tapes: with and without steel tape reinforcement. The results showed that tapes with reinforcement presented small critical current degradation as a function of the number of thermal cycles whereas tapes without reinforcement exhibited steadily critical current degradation caused by the propagation of cracks. The n-index followed the same critical current behavior. © 2006 IEEE.16210271030Masur, L.J., The status of commercial and developmental HTS wires (2003) Phys. C, 392-396, pp. 989-997Van Eck, H.J.N., Vargas, L., Ten Haken, B., Ten Kate, H.H.J., Bending and axial strain dependence of the critical current in superconducting BSCCO tapes (2002) Superconductor Science and Technology, 15, pp. 1213-1215Ahoranta, M., Lehtonen, J., Kovac, P., Husek, I., Melisek, T., Effect of bending and tension on the voltage-current relation of Bi-2223/Ag (2004) Phys. C, 401, pp. 241-245Shin, H.S., Oh, S.S., Ha, D.W., Degradation behavior of critical current in Bi-2223 tapes in bending-tension strain mode (2004) Phys. C, 412-414, pp. 1107-1113Sugano, M., Osamura, K., Stress-strain behavior and degradation of critical current of Bi2223 composite tapes (2004) Phys. C, 402, pp. 341-346Ochiai, S., Damage evolution under bending and tensile stress and its influence on critical current of Bi2223/Ag superconducting composite tape (2004) J. Nucl. Mat., 329-333, pp. 1585-1589Ochiai, S., Hayashi, K., Osamura, K., Influence of thermal cycling on critical current of superconducting silver-sheathed high Tc oxide wires (1993) Cryogenics, 31, pp. 954-961Ha, H.S., The effect of thermal cycling and axial strain on the IC degradation of multi-filamentary Bi-2223/Ag tapes (2004) Phys. C, 412-414, pp. 1096-1100Shigue, C.Y., Baldan, C.A., Oliveira, U.R., Carvalho Jr., F.J.H., Filho, E.R., Effect of combined bending strain and thermal cycling on the voltage-current characteristic curves of Bi-2223 tapes (2005) IEEE Trans. Appl. Supercond., 15, pp. 2492-2944Salazar, A., Pastor, J.Y., Llorca, J., Fatigue behavior of multifilamentary BSCCO2223/Ag superconducting tapes (2004) IEEE Trans. Appl. Supercond., 14, pp. 1941-1947Sørensen, B.F., Horsewell, A., Skov-Hansen, P., In situ observations of crack formation in multi-filament Bi-2223 HTS tapes (2002) Phys. C, 372-376, pp. 1032-1035Malachevsky, M.T., D'Ovidio, C.A., SEM investigation of the critical current degradation onset in BSCCO-2223 multifilamentary tapes submitted to bending (2005) Supercond. Sci. Technol., 18, pp. 289-293Ghosh, A.K., V-I transition and n-value of multifilamentary LTS and HTS wires and cables (2004) Phys. C, 401, pp. 15-21Young, W., (1989) Roark's Formulas for Stress and Strain, , New York: McGraw-Hill