Aim: To determine the shaping ability and cleaning effectiveness of Revo-S and Typhoon CM wire rotary instruments in-terms of degree and direction of canal transportation.Methodology: Mesiobuccal canal of 70 extracted maxillary molars were divided into 2 groups of 35 teeth each and were then prepared using Revo-S and Typhoon CM wire rotary instruments after all teeth showed the following criteria, mesiodistal (clinical) canal curvature range between 25º- 40º, the radius of curvature of the canal range from 4 - 10 mm, the length of the curved part of the canal between 6 - 8 mm. Pre- and post-instrumentation measurements of root dentine thickness for 40 teeth were assessed using CBCT to determine degree of transportation and centering ability while 30 teeth were assigned for evaluation of cleanliness using stereomicroscope and SEM. Thirty samples (15 from each group) were observed under stereomicroscope for gross detection of the dentin surface. Five samples from each group were randomly selected for examination of smear layer under SEM.Results: The mean and standard deviation values of canal transportation were 0.26 ± 0.29 mm and 0.05 ± 0.05 mm at 3mm level, 0.20 ± 0.17 mm and 0.06 ± 0.05 mm at 5 mm level and 0.21 ± 0.21 mm and 0.06 ± 0.07 mm at 8 mm level after using Revo-S and Typhoon CM wire respectively for canal transportation while for centering ability the mean and standard deviation values were 0.38 ± 0.28 and 0.58 ± 0.19 at 3 mm level, 0.57 ± 0.22 and 0.60 ± 0.28 at 5 mm level and 0.65 ± 0.29 and 0.63 ± 0.26 at 8 mm level after using Revo-S and Typhoon CM wire respectively. For canal cleanliness, the use of Typhoon (CM wire) rotary instrument resulted in significantly less debris compared to canal preparation with Revo-S rotary instrument after evaluation with stereomicroscope while by SEM evaluation, completely cleaned root canals were never found. In general, the use of Typhoon (CM wire) rotary instrument resulted in significantly less debris compared to canal preparation with Revo-S rotary instrument. In terms of smear layer, Typhoon (CM wire) rotary instrument resulted in significantly less smear layer compared with Revo-S rotary instrument.Conclusions: It can be concluded that Typhoon Infinite flex CM wire showed less canal transportation, better centering ability and better cleaning effectiveness compared to Revo-S NiTi rotary instruments.