Fragmentation of isoxazole molecules by electron impact excitation, that produces excited atomic and molecular fragments, has been studied using the optical excitation technique. Excited hydrogen atoms H(n), n = 4-7, have been detected by observation of the H-beta to H-epsilon lines of the Balmer series. The diatomic CH(A(2)Delta) and CN(B-2 Sigma(+)) fragments have been identified by their A(2)Delta -> X-2 Pi(r) and B-2 Sigma(+) -> X-2 Sigma(+) emission bands, respectively. The appearance energies for the H(n = 4), CH(A(2)Delta) and CN(B-2 Sigma(+)) have been measured to be 21.9, 14.0 and 10.6 eV, respectively. Absolute emission cross sections have been also obtained for the fragments in electron energy ranges from their respective appearance thresholds up to 85 eV. Possible fragmentation processes are discussed. (C) 2010 Elsevier B.V. All rights reserved.