A single-point optical probe is developed that can accurately obtain local gas holdup in a gas liquid stirred tank across a wide range of operating pressures, temperatures, and fluids. It is found that the probe orientation to the flow in a stirred tank can cause underestimations in gas holdup if only a single probe orientation is used. The probe is also able to capture the complex flow pattern in the vessel. This allows improved understanding of optical probes and stirred tanks and generation of data at elevated pressure and temperature conditions needed for development of new fundamental models.