Porous ceramics based on refractory double oxides are promising for light-weight structural components and high-temperature filter materials. In this study, porous MgTi₂O₅ ceramics with pseudobrookite-type structure have been prepared by in situ processing (viz. reactive sintering). High-temperature XRD revealed the in situ reaction behavior of the mixed powder, and indicated suitable sintering temperatures to obtain single phase MgTi₂O₅ (≥1000°C). Uniformly porous MgTi₂O₅ ceramics with very narrow pore-size distribution at the diameter of ∼1 µm were obtained by the pyrolytic reactive sintering at 1000–1200°C, where decomposed CO₂ gas from a carbonate source acted as an intrinsic pore forming agent. Thermal expansion behavior of bulk porous MgTi₂O₅ (porosity: 42%) is also discussed.