The environmental consequences associated with the release of carbon dioxide, and our continued reliance on fossil fuels, have real-world ramifications. Mitigating these risks is therefore an ongoing and central problem in the sustainable chemical sciences, and several approaches to this problem have been proposed. These include, among others, the direct sequestration of carbon dioxide into porous materials or its chemical transformation into added-value commodities by a catalytic substrate. We explore the latter in this work, which is broadly classified as small-molecule activation. Carbon dioxide itself exists as the most oxidised form of carbon, and a large amount of energy is therefore required to overcome its inherent inertness. We are interested in the insertion of carbon dioxide into reactive organometallic complexes containing strained cyclic ring systems that are predisposed towards further reactivity. Herein, we present a series of ruthenium-centred metallalactones of the form, cis‑[Ru(OC(=O)CH=CR-κ2-C,O)(PMe3)4] (R = Ph, Me, H; PMe3 = trimethylphosphine). Each complex presented in this work has been structurally characterised by X-ray crystallography and their in situ catalytic activity has been determined by nuclear magnetic resonance spectroscopy which, upon hydrogenation, reductively eliminate aliphatic carboxylic acids.