Coumarin dyes are a diverse family of dyes containing the coumarin functional group and a primary, secondary, or tertiary amine. Most of these dyes are fluorescent and the analysis of dyes, especially in fabrics and fibers, is of forensic interest. The analysis methods employed here are high pressure liquid chromatography (HPLC) and electrospray – mass spectrometry – mass spectrometry (ESI-MS-MS). A gradient elution by HPLC has been developed to separate seventeen coumarin dyes. This study then examines conditions for formation of the (M+H+) peak from ESI-MS and that parent peak's collision-induced dissociation (CID). The coumarins were studied for their fragmentation patterns in ESI-MS-MS and mechanisms of dissociation are proposed.