A unique reaction between H2S and a selenenyl sulfide containing benzoate ester template was discovered. This reaction could be specifically triggered by H2S and lead to ester bond cleavage. The reaction was not affected by the presence of thiols such as glutathione and cysteine. With this reaction, a series of fluorescent probes were synthesized and evaluated. The probes exhibited high sensitivity/selectivity for H2S in both buffers and cells.