The effect of high inlet solid loadings on cyclone pressure drop and separation efficiency was studied. The particles used were FCC catalyst. An extended range of concentrations, up to 20 kg of solids/kg of gas was used, well beyond the loading range reported before. The average entrance velocities were 7, 18 and 27 m/s. The experiments showed that, in the range of concentrations tested, the cyclone pressure drop for the solids laden air flow was about 47% of that for clean air. A trend of increasing separation efficiency with concentration was observed, up to 12 kg of solids/kg of gas, above which, the efficiency decreased. At test conditions, the collection efficiency was higher for the entrance velocity of 18 m/s than for 27 m/s.