A high intensity pulsed DC discharge source for OH radical beam was developed by the systematic optimization for geometry of the discharge source and for the operation conditions. OH radicals produced in the DC discharge source were state-selected by an electrostatic hexapole field. The maximum OH flux in the lowest \J, Omega, M> = \3/2, 3/2, 3/2> state was directly measured to be 8.5 x 10(14) radicals cm(-2) s(-1) at the beam crossing point of 150 cm downstream from nozzle by a saturated laser-induced fluorescence spectroscopy for the Q(1)(1) transition in A(2)Sigma <-- X(2)Pi(3/2) transition. (C) 2003 Elsevier B.V. All rights reserved.