Measurements were made of the radiative association kinetics of NO+ with 3-pentanone as a function of temperature from 300 to 400 K, using the Fourier-transform ion cyclotron resonance ion-trapping mass spectrometer. Both the absolute association rate and the temperature dependence were compared with the predictions of two levels of theory, a simple RRKM-based approach previously applied to several systems. and a new, detailed variational transition state theory (VTST) approach incorporating ab initio calculations of vibrational frequencies and IR emission intensities. The analysis by the VTST approach was considered reliable and successful enough To justify averaging with a previous thermochemical determination to give a revised binding energy for tile complex of 41.6 +/- 2 kcal mol(-1) (1.80 +/- 0.1 eV). The VTST approach also gave excellent agreement with the observed temperature dependence. The RRKM estimate of the rate was in satisfactory agreement with observation, but the slope of the temperature dependence plot predicted by this simple theory was slightly too sleep. The competing endothermic charge transfer channel, whose rate was observed to increase slightly with temperature, was included in the VTST modeling. The combination of radiative association kinetic data with ab initio calculations and VTST modeling as done here appears promising as a new route to ion-neutral complexation thermochemistry.