© 2022 Elsevier B.V.In this work, synthesis and characterization of sulfonium salt photoinitiators (PIs) possessing coumarin skeleton are reported. Photochemical and photophysical properties were investigated by various spectroscopic and computational investigations. PIs exhibit excellent photolysis and outstanding initiating efficiency for cationic, free radical and hybrid photopolymerizations without any additives at UV and visible region. The possible mechanism of photolysis was verified by detailed spectral, real-time 1H-nuclear magnetic resonance (NMR), gas chromatograph–mass spectrometer (GC–MS) and computational investigations. The solubility and activity of active species can be regulated by changing the length of the aliphatic chain on the sulfur atom. Differential scanning calorimetry (DSC) studies on hybrid polymerizations involving epoxy and acrylic monomers confirmed excellent thermal stability of the mixed system. It is anticipated that these PIs with such properties will have broad applications involving photopolymerization processes.