Attaining controlled, biocompatible H2S donors poses significant challenges. We developed Bhc-TCN-Ph, a photoactivated H2S donor derived from 6-bromo-7-hydroxycoumarinmethyl thiocarbonate. Upon 365 nm light exposure, COS is released, generating H2S and coumarin fluorescence for visualization. This process produces no electrophilic by-products. In vitro evaluations reveal good cytochemical and cytocompatibility characteristics.