The reactions of silyl and silyl-d(3) radicals with nitric oxide, SiH3 + NO --> SiH3NO (1) and SiD3 + NO --> SiD3NO (2), have been studied using pulsed excimer laser photolysis coupled with time-resolved photoionization mass spectrometry over the temperature range 301-817 K. The rate constants were measured in the ranges 0.75 x 10(16) less than or equal to [He] less than or equal to 32.0 x 10(16) molecules cm(-3) and 301 less than or equal to T less than or equal to 611 K. Both reactions are in the pressure falloff regions considerably far from the true low-pressure limit. RRKM fittings using the Tree factorization approach yielded the low-pressure limit and high-pressure limit rate constants : (1,tri) = (3.12 +/- 0.12) x 10(-29)(T/298)(-2.96+/-0.09) cm(6) molecule(-2) s(-1), k(2,tri) = (9.02 +/- 0.40) x 10(-29)(T/298)(-3.36+/-0.11) cm(6) molecule(-2) s(-1), k(1,inf) = (3.9 +/- 1.1) x 10(-11)(T/298)(-1) cm(3) molecule(-1) s(-1), and k(2,inf) = (5.0 +/- 1.3) x 10(-11)(T/298)(-1) cm(3) molecule(-1) s(-1). Equilibrium constants were measured in the temperature range 711-817 K. The standard enthalpies of reactions 1 and 2 were determined using the third law method. The bond energies determined are DH0 degrees(H3Si-NO) = 153.7 +/- 5.7 kJ mol(-1), DH(298)degrees(H3Si-NO) = 158.9 +/- 5.7 kJ mol(-1), DH0 degrees(D3Si-NO) = 156.1 +/- 5.7 kJ mol(-1), and DH(298)degrees(D3Si-NO) = 160.8 +/- 5.7 kJ mol(-1). This value of DH0 degrees(H3Si-NO) is ca. 30 kJ mol(-1) higher than previous estimates. Ab initio structural parameters were used to calculate the thermodynamic functions of SiH3, SiD3, SiH3NO, and SiD3NO. Both the singlet and the low-lying triplet states were taken into account for the adduct molecules. The calculated thermodynamic functions were used to obtain the standard entropies of the reactions 1 and 2 : Delta S(298)degrees(rxn 1) = 143.1 J mol(-1) K-1 and Delta S(298)degrees(nm 2) = 146.0 J mol(-1) K-1. The rate constants of the reaction SiH3NO + NO --> products (3) were measured in the temperature range 301-611 K : k(3) = (2.95 +/- 0.38) x 10(-13)(T/298)(-1.59+/-0.29) cm(3) molecule(-1) s(-1).