Reactions of laser-ablated Rh and Ru atoms with N2O molecules in excess argon have been investigated using matrix-isolation infrared spectroscopy. Rhodium and ruthenium nitrous oxide complexes, M(NNO)(x) (M = Rh, Ru; x = 1, 2), have been observed and identified on the basis of isotopic shifts, mixed isotopic splitting patterns, and CCl4-doping experiments. Density functional theory calculations have been performed on the products. The overall agreement between the experimental and calculated vibrational frequencies, relative absorption intensities, and isotopic shifts supports the identification of these species from the matrix infrared spectra. Furthermore, a plausible reaction mechanism for the formation of the products has been proposed.