An improved hydroformylation process involving reacting one or more reactants, such as an olefin, with carbon monoxide and hydrogen in the presence of a hydroformylation catalyst, to produce a reaction product fluid comprising one or more products, preferably aldehydes; wherein said process is conducted in a region of the hydroformylation rate curve that is negative or inverse order in carbon monoxide, which is sufficient to prevent and/or lessen deactivation of the hydroformylation catalyst; and wherein total pressure is controlled at a predetermined target value and/or vent flow rate is controlled at a predetermined target value, by adjusting a flow of a carbon-monoxide containing inlet gas, so as to prevent and/or lessen cycling of process parameters, e.g., reaction rate, total pressure, vent flow rate, and/or temperature.