A multi-stage catalyst development approach is used to evaluate and optimize fluidizable tar reforming catalysts for conditioning syngas from biomass gasification. Previous work showed that catalyst fluidization is required to efficiently reform biomass-derived pyrolysis oil and its fractions to syngas as fluidization optimizes contact between catalyst particles and feedstocks while reducing coke formation. Biomass-derived tars like pyrolysis oils are also complex, largely aromatic feedstocks that require fluidization to improve reforming efficiency. Because industrial reforming catalysts are designed for fixed-bed operations and not for fluidized processing, attrition resistant supports and catalysts required development. We identified and tested particulate aluminas for attrition resistance under fluidized steam reforming conditions and prepared nickel-based catalysts from the strongest supports. The performance of these catalysts was tested in a microactivity test system (MATS), which used I g catalyst quantities, had high throughput, and measured oxidation, reduction and model tar compound steam reforming. Promising candidates from MATS screening were next evaluated in a laboratory-scale fluidized bed reactor with 250 g of catalyst using more realistic flow conditions and input streams. A 60 kg batch of the best catalyst identified in the laboratory fluid bed was then prepared and evaluated for biomass-derived syngas conditioning in a pilot-scale reformer. Fresh and used catalysts were characterized with scanning electron, energy dispersive X-ray, and inductively coupled plasma spectroscopies. The most active and attrition resistant catalyst identified through multi-stage testing contains nickel, magnesium and potassium on 90% alpha alumina particles of 100-400 mu m size. (c) 2006 Elsevier B.V. All rights reserved.