The kinetics of the gas-phase reactions of phosphorus oxychloride [P(O)Cl-3], methylphosphonic dichloride [CH3P(O)Cl-2], dimethyl phosphonate [(CH3O)(2)P(O)H], and trimethyl phosphite [(CH3O)(3)P] with the OH radical were measured at 298 +/- 2 K and 1 atm (similar to740 Torr) of dry air by a relative rate method which employed the photolysis of CH3ONO as the source of OH radicals and analysis of the reaction mixtures by in-situ Fourier transform infrared (FT-IR) spectroscopy. The measured values of the OH radical reaction rate constants (cm(3) molecule(-1) s(-1)) are the following: P(O)Cl-3, < 4 x 10(-14); CH3P(O)Cl-2, (6.4 +/- 2.1) x 10(-14); (CH3O)(2)P(O)H, (5.08 +/- 0.53) x 10(-12), and (CH3O)(3)P, (7.1 +/- 0.9) x 10(-10), corresponding to estimated tropospheric lifetimes of > 290 days, 180 days, 2.3 days, and 0.016 day, respectively, for the reactions of these compounds with OH radicals. In support of the OH radical rate constant measurement for (CH3O)(3)P, the absolute rate constant for the NO2 + (CH3O)(3)P reaction was measured and determined to be (3.8 +/- 0.4) x 10(-18) cm(3) molecule(-1) s(-1) at 298 +/- 2 K. The products of the reaction of dimethyl phosphonate with the OH radical and those of trimethyl phosphite with the OH radical, NO2, and O-3 were investigated by FT-IR spectroscopy and atmospheric pressure ionization mass spectrometry (API-MS).