The thermally induced decomposition of phenylsilane has been investigated by three different experimental methods : a static method, a comparative rate-single pulse shock tube (CR-SPST) method, and a very low-pressure pyrolysis (VLPP) method. Decomposition is mainly heterogeneous under static conditions but appears homogeneous in the other two systems. Homogeneous dissociations occur by two channels with yields, 2 PhSiH(3) --> H-2 (1) + PhSiH, phi(i) similar to 0.84 +/- 0.04; PhSiH(3) --> PhH (2) + SiH2, phi(2) similar to 0.16 +/- 0.04. Coupling of CR-SPST and homogeneous static reactor data spanning temperatures from 693 to 1236 K for the benzene formation channel and adjusting for falloff by RRKM methods gives high-pressure Arrhenius parameters of A(1) = 10(14.0 +/- 0.4) E(1)= 59.3 =/- 2.1 and A(2) = 10(13.9 +/- 0.2) E(2) = 62.0 +/- 0.9 (A in s(-1) and E in kcal/mol) for the two primary dissociation channels. These parameters yield RRKM calculated rate constants under VLPP conditions which agree within the errors with experimental rate constants.