A velocity-variable highly intense pulsed supersonic CH (X-2 Pi) radical beam source was newly developed for the study on the collision energy dependent reaction dynamics of the state-selected CH radical. CH radicals were state-selected by an electrostatic hexapole field. The focusing curves and the CH flux intensities for the vertical bar J, F-i, M > states were measured by a saturated laser-induced fluorescence spectroscopy. As a demonstration, the rotational state dependence of the reaction cross section of CH + O-2 - OH(A) + CO reaction was determined at the collision energy of 0.06 eV. (c) 2006 Elsevier B.V. All rights reserved.