The oxygen storage capacity of Ce0.2Zr0.8O2 solid solutions, prepared by different synthesis routes and aged at 1000 degreesC, is investigated by means of temperature-programmed reduction, total- and dynamic-OSC measurements. The use of CO and H-2 as reducing agent is compared under dynamic conditions. It is observed that the dynamic OSC is critically dependent on sample pre-treatment and the nature of the reducing agent in the texturally unstable sample. In contrast, on a thermally stable Ce0.2Zr0.8O2 only minor effects of the pre-treatment upon dynamic OSC are noticed.