The porous phase of plasma-sprayed alumina was characterized using mercury intrusion porosimetry, water immersion methods, and small-angle neutron scattering. A comparison of the results shows that the intrusion techniques did not yield a full porous phase characterization. It has been found that while the amount of closed porosity was 1.4% (+/- 0.5%) of the sample volume, this volume accounted for only 60% of the total internal surface area. The smallest void diameter was found to be 10 nm.