Superplastic-forming processes are simulated with finite-element analysis in the convective coordinate system. The finite-element code developed is applied to blow-forming processes for demonstration of its validity by predicting the optimum forming pressure cycle. The numerical results provide the pole height and intermediate deformed shapes with variation of the forming time, as well as thickness distribution. The results are compared with those from the experiment and finite-element analysis with a continuum element. The finite-element code is applied to the analysis of a superplastic-forming/diffusion-bonding (SPF/DB) process of four-sheet sandwich parts. The result shows that the deformed shape with the three-dimensional analysis is different from that with the two-dimensional plane strain because of the end effect, and so is the thickness distribution. The analysis enables accurate prediction of thickness distribution, which is necessary for the good design of multi-sheet sandwich parts such as an aircraft part. (C) 1999 Elsevier Science S.A. All rights reserved.