Platinum oxides have wide range of technological applications from catalysis to nanoelectronics to electrochemistry. However, growing crystals of or even synthesising the powder of ternary and quaternary platinate compounds is challenging due to the inert nature of platinum and the thermal instability of platinum oxide and other platinate compounds. Via experimenting with molten hydroxide fluxes a new platinate compound, (K,Ca)0.67PtO2, was discovered. Single crystal and powder x-ray diffraction indicates that (K,Ca)0.67PtO2 has a delafossite structure with only one type of platinum environment. We propose to use HRPD to collect powder neutron diffraction data at 4K, 100K, 200K and 300K to investigate important aspects of the structure such as Ca/K/vacancy composition and order, and possible low temperature electronic instabilities.