Yields of light fission products (A = 68, 70-84, 87, 88, 94, 96, 98, 102 and 106-108), their kinetic energies and nuclear charge distributions (A = 71-84, 87 and 88) in the thermal neutron induced fission of the odd-Z nucleus Am-242m(Z = 95) were measured using the mass-separator Lohengrin at the Institute Laue-Langevin in Grenoble (France). The mass yield curve shows a fine structure at A = 70, probably due to shell and/or odd-even effects affecting also the nuclear charge distribution. The analysis of isotopic chain yields gives evidence for a very low excitation energy of the lightest fission fragments observed. A preferential formation of fragments with even Z is found for this odd-Z compound nucleus, Calculated values for the local odd-even effect are comparable with those for the neighbouring even-Z fissile nuclides and increase from 13% to 30% with increasing asymmetry of the mass split (A(L) = 84 to 68 and Z(L) = 35 to 28). The neutron odd-even effect shows a similar but less pronounced behaviour. (C) 1999 Elsevier Science B.V. All rights reserved.