The collisional quenching of OH (A 2[Sigma]+, v'=0) is studied by laser-reduced fluorescence in the burnt gases of low-pressure (7 Torr) stoichiometric H2/O2/N2O flames. The temperature of these flames is adjusted between 1200 and 2300 K by altering the O2/N2O mixing ratio. The variation of the quenching rate constant with rotational level in the OH(A) for H2O collider is substantially less at 2300 K than previously observed at room temperature. The OH(A) quenching rate constant by atomic hydrogen at 1200 K is estimated k = 8 × 10 - 10 cm 3 s - 1.