Toroid NMR probes can be routinely operated at 300 atm and up to 250 degrees C. Such operating conditions make these probes well suited for the in situ examination of catalytic industrial processes. These probes have been employed to examine phosphine substituted (Shell-type) and unsubstituted cobalt carbonyl oxo catalysts under catalytic and non-catalytic conditions in a variety of solvents. The solvents include cyclohexane, benzene, dioxane, 2-methylpropanol, supercritical carbon dioxide (scCO(2)), and scCO(2)/toluene mixtures. The high-pressure/high-temperature probes allowed the observation of precatalytic equilibria under high carbon monoxide pressures in the presence and absence of hydrogen and/or free phosphine.