Introduction: A colour additive is a dye incorporated in contact lenses for cosmetic reasons. The information of the additive’s metallic elements and the impact on the human cornea is however limited. We aimed to characterise the metallic elements used as colour additives in cosmetic colour contact lenses (Cos-CCLs) and to investigate their effects on the human corneal epithelial cells. Methods: Two contact lens brands, Freshkon (FK) and AirOptix (AO) of three colours (brown, green, grey) were studied. A Field Emission Scanning Electron Microscope equipped with Energy Dispersive X-ray Spectroscopy (FESEM-EDX) was used to characterise the chemical elements used as the colour additives. The findings on the chemical elements were compared between the Cos-CCLs and their respec- tive clear contact lens counterparts. The effects of Cos-CCLs and clear contact lenses on human corneal epithelial cells (HCECs), in vitro, was assessed using an MTT-assay over an 8-hour time period. Results: Five key metallic constituents were identified in all Cos-CCLs but were not found in clear contact lenses. The most frequently detect- ed metallic additive was iron. HCEC viability was detrimentally affected more by Cos-CCLs than the clear contact lenses. Conclusion: Dissimilar metallic additives combinations are used by manufacturers to achieve the different coloured effects in a range of coloured contact lenses. Vitro data exhibits a detrimental effect of metallic additives on the human corneal epithelial cells. Nevertheless, more real case scenarios are still required to support our toxicity investigation and inference.