Primary reactions in irradiated single crystals of salts of tartaric acids, a-amino acids and monochloroacetic acid have been studied by pulse radiolysis and ESR spectroscopy. The primary products are formed by the loss or capture of an electron and are referred to as oxidation and reduction products. The pulse radiolysis technique gives information about the optical properties and the kinetics of decomposition of the primary products. The ESR spectroscopy technique is used for the identification of the products. By combining the techniques of pulse radiolysis and ESR it is possible to arrive at the reaction schemes and the activation energies for the decomposition of the primary products. The kinetics of decarboxylation of the oxidation products, and dehydration , deamination and dechlorination of the reduction products have been determined.