This study describes the within- and between-laboratory reproducibility (WLR and BLR) of a Time-to-Toxicity (TTT) approach for chemicals based on the SkinEthicTM HCE tissue construct, capable to distinguish chemicals that do not require classification for serious eye damage/eye irritation (No Cat.) from chemicals that require classification for eye irritation (Cat. 2), and serious eye damage (Cat. 1).