Objective Morning breath is a temporary and unpleasant malodour sourced from the mouth, which occurs upon awakening. This double‐blind, crossover, randomized clinical trial aimed to evaluate the bad‐breath suppression of three commercially available mouthwashes: Mentadent Professional® Chlorhexidine 0.05% with vitamin C (ChxC), Meridol Alito Sicuro® (SnF2) and CB12® (ZnChx) compared to a placebo (PbO) on morning halitosis. Methods Thirty‐two subjects refraining from oral hygiene practices for 12 h before the evaluation, performed a 30‐s rinse with 15 ml of mouthwash, followed by a 5‐s gargle, in the evening before bedtime. In order to assess morning halitosis, visual inspection (Winkel Tongue Coating Index), organoleptic (Rosenberg index) and chromatographic measurements were used. Gas chromatography was carried out by means of a dedicated device, the Oral Chroma. The recorded measurements have to be considered solely after the rinse since no data about the pre‐exposure were available. A washout period of 1 week passed between one administration and the next. Results The mean value of the organoleptic indices after administration of ChxC mouthwash is similar to ZnChx, SnF2 and PbO values. Thus, no statistically significant differences were recorded among the mouthwashes and PbO. Nevertheless, ChxC seems to be more efficient in comparison with the PbO regarding VSCs levels analysed with Oral Chroma, (CH3SH; p = 0.0081) and [(CH3)2 S; p = 0.0003]. Conclusion Considering our limited sample, instrumental examination demonstrated that the use of the analysed mouthwashes can result in low VSCs levels after 12 h from a single rinse. Furthermore, the highest number of patients (n = 14) were proved to be free from bad smell after using a single administration of ChxC with respect to the other commercial products. The other tested mouthwashes did not show better performances with respect to the placebo after a single rinse.