This specification covers the isobutane thermophysical property tables which are used in the calculation of the pressure-volume-temperature (PVT), thermodynamic, and transport properties of isobutane for process design and operations. Tables are provided for gaseous and liquid isobutane at temperatures between 135 and 600K at pressures to 35 MPa. These tables apply directly only to pure gaseous and liquid isobutane. However, it is expected that mathematical models and tables shall be useful for the thermophysical properties of mixtures containing isobutane, such as natural gas. These thermophysical property tables are: Thermophysical Properties of Coexisting Gaseous and Liquid Isobutane, in SI units and Thermophysical Properties of Isobutane, along isobars, in SI units.