Rate constants for the collisional quenching of spin-orbitally excited Ck(P-2(1/2)) atoms by H2O. D2O, and H2O2 were determined at similar to 295 K using laser-flash photolysis and laser-induced fluorescence techniques in the vacuum ultraviolet energy region. The rate constants reported for the quenchers of H2O, D2O, and H2O2, are (3.9 +/- 0.3) x 10(-11) , (4.7 +/- 0.3) x 10(-11), and (3.1 +/- 0.3) x 10(-10) cm(3) molelcules(-1) s(-1), where the uncertainties correspond to 1 sigma, respectively. (c) 2005 Elsevier B.V. All rights reserved.