We report a novel dual-lumophore oxygen sensor incorporating two lumophores: (1) the platinum(II) cyclometalated complex of the N;C;N-coordinating ligand 1,3,5-tri-(2-pyridyl)benzene and (2) Platinum octaethylporphyrin, which differ in both their emission colours and oxygen sensitivities. Sensor response is given by a dramatic change in emission colour, from red to green at different oxygen concentrations, due to the complete or partial luminescence quenching of one or both of the sensing elements. This approach enables the simple and rapid evaluation of the O2 concentration present, making it applicable to commercial technologies such as modified atmosphere packaging.