With this report we describe the increase in specific surface area of high purity batches of three phases of bismuth molybdate catalysts by the combination of two techniques: a complexation method and spray drying. Thermal decomposition of the citric acid in the precursor is the origin of the increase in surface area of the catalysts. The optimal amounts of added citric acid were established for both complexation and spray drying methods. Furthermore, the spray drying was improved by adding sorbitol or changing the pH of the precursor solutions. The obtained high surface area catalysts obviously exhibit higher catalytic activity, opening promising applications of the methods. (C) 2004 Elsevier B.V. All rights reserved.