Photodissociation pathways for 3,4-dichloro-1,2,5-thiadiazole was investigated in its ground state at various wavelengths in the UV region. The photolysis products were identified by the UV absorption and emission spectroscopy. Molecular chlorine (Cl-2) elimination was observed using absorption methods in the UV region. UV absorption and quantum calculation confirms the migration of chlorine atom and subsequent ring opening to form NC-C(Cl-2)-N=S isomer. Multiphotonic excitation leading to the UV emission in the vicinity of 389 nm was observed due to the formation of CN(B-2 Sigma(+)) moiety. New UV absorption bands observed at 255 and 290 nm were assigned to the its isomer NC-C(Cl-2) N=S. (C) 2016 Elsevier B.V. All rights reserved.