A simple method of synthesis of LnMn(2)O(5) (Ln = Nd, Pr) is presented. Mixtures of sodium molybdate, molybdenum(VI) oxide, MnCO3, and Nd2O3 or Pr6O11 were electrolyzed for 3-24 h at 930-1020 degreesC with platinum electrodes. Single crystals of LnMn(2)O(5) (Ln = Nd, Pr) with an edge up to 1.5 mm formed at the anode. The crystal structures of NdMn2O5 and PrMn2O5 were refined by Rietveld profile analysis in space group Pbam (Z = 4); the lattice parameters are a = 7.4970(2) Angstrom, b = 8.6086(2) Angstrom, c = 5.6963(1) Angstrom and a = 7.5384(2) Angstrom, b = 8.6319(2) Angstrom, c = 5.7022(1) Angstrom, respectively. The magnetic susceptibility measurements show an antiferromagnetic transition at 25 K for PrMn2O5. Both the NdMn2O5 and PrMn2O5 crystals are insulating. (C) 2000 Elsevier Science Ltd. All rights reserved.