Aim: To evaluate the effects of two preprocedural mouthrinses, hydrogen peroxide (H₂O₂) and povidone iodine (PI) on the surface characteristics and mechanical properties of nickel–titanium (NiTi) and stainless steel (SS) orthodontic archwires. Materials and methods: Five wire specimens were used, each (0.016” NiTi, 0.016” SS wires, 0.016 × 0.022” NiTi and 0.016 × 0.022” SS wires) specimen was cut into 30 mm lengths and immersed in 9% of artificial saliva and 91% of two preprocedural mouthrinse solutions: 1.5% hydrogen peroxide mouthwash, 0.2% povidone-iodine mouthwash, and distilled water (control group) for 90 minutes and incubated at 37°C. The wire specimens were then subjected to a three-point bending test for mechanical testing and viewed under a scanning electron microscope (SEM) to evaluate their surface characteristics. The collected data were analyzed using one-way analysis of variance (ANOVA) and Bonferroni post hoc test. Results: The results showed a significant increase in the flexural modulus (E) of Nitinol wires in povidone-iodine gargle (p < 0.05) and a significant increase in the E of stainless steel wires in hydrogen peroxide mouthwash (p < 0.05). Analysis using SEM showed varying qualitative surface changes in the form of corrosion, voids, and ridges on the wires after exposure to both the mouthwashes. Conclusion: Though there were significant changes in the flexural modulus of archwires for both the mouthwashes, hydrogen peroxide did not show a significant difference in the E of wires at most of the deflection intervals when compared with the other two solutions, hence, could be used in orthodontic patients as an effective preprocedural mouthrinse. Clinical significance: Preprocedural mouthrinses can cause surface irregularities on the wires which in turn lead to an increase in friction at the bracket–wire interface, thereby disrupting effective tooth movement and extending the orthodontic treatment time.