Optimization of zirconia-supported boria catalyst for the Beckmann rearrangement of cyclohexanone oxime was studied with the control of three preparation parameters: the temperature of support pre-calcination (PCT: 110-700 degreesC), the calcination temperature for the catalyst activation (CAT: 250-600 degreesC), and the load level of boria. When the CAT is limited no higher than 500 degreesC, the lactam yield increases with the PCT and shows maximum numbers with PCT = 350-500 degreesC. This effect of PCT seems not important for the catalyst preparation when the late catalyst activation is done with CAT as high as 600 degreesC. Catalyst preparations with CAT = 600 degreesC agrees with the model that the optimized catalyst has, on the average, about two surface overlayers of boria on the support. Another part of this work focused on effects of the reaction solvents and carrier gases. A remarkable benefit for the lactam synthesis is observed with proper combination of the solvents and carrier gases: (C) 2000 Elsevier Science B.V. All rights reserved.