Abstract—Some features of chemiluminescence important for quantitative studies of the phenomenon are discussed. Parallel excitation reactions may lead to several sorts of emitters. Energy transfer from and quenching of excited states may be responsible for the peculiar behaviour of chemiluminescent systems. These points are illustrated by results for a model reaction: thermal decomposition of dicyclohexylperoxydicarbonate (DCHPC) in the presence of O2with or without methylethylketone and an activator, 9,10‐dibromoanthrac