At temperature range of 25-800 degrees C, in situ X-ray diffraction studies on Bi0.8-xPrxBa0.2FeO3 (x <= 0.1) ceramics are performed. The unit cell symmetry remains unchanged, while temperature dependence of lattice parameters and unit-cell volumes vary. There are no phase decomposition and structural phase transition detected in the system, which indicate that Pr, Ba co-doping may stabilize the structure of BiFeO3 ceramic. The unit cell thermal expansion and thermal expansion coefficients are positive. However, for sample with x = 0.1, i.e., Bi0.7Pr0.1Ba0.2FeO3, the unit cell structural stability decreases, and the thermal expansion coefficient increases. The thermal expansion coefficients abnormal around the Neel temperature are observed, which may suggest a possible antiferromagnetic-paramagnetic transition. It is probably the explanation for their low thermal expansion coefficient during the heating process. (C) 2015 Elsevier B.V. All rights reserved.