The rate constant for the CH + H2O reaction has been measured in a fast-flow reactor to be (0.9 +/- 0.4) x 10 (11) cm(3) molecule (1) s (1) at 330 K. The product branching ratio of H atoms probed by resonance fluorescence is determined to be 100%. Quantum chemistry and statistical calculations show that the rate limiting process is the isomerisation of the HCOH2 adduct to H2COH and allow us to propose k = (2.8 +/- 1.4) x 10 (11)(T/300) (1.22) (+/-) (0.07)exp(-(12 +/- 12)/T) cm(3) molecule (1) s (1) in the range 100-700 K for the rate constant of CH + H2CO -> H + H2CO and H-2 + H + CO. (C) 2009 Elsevier B.V. All rights reserved.