The CAPE-OPEN (CO) project have published CORBA and COM open interfaces in order to enable native components of a process simulator to be replaced or plugged from those of independent sources. Until now the major effort of this project is regarded with sharing thermodynamic and unit operation packages. For this reason, the set of interfaces for numerical solvers is not mature yet. In this work the set of CORBA interfaces for sharing numerical solvers is treated. Some inconsistencies found at the original CO set of interfaces were corrected and simplifications were proposed. The performance impact in using the interfaces was studied and the usability of the simplified set of interfaces was tested. (C) 2004 Elsevier Ltd. All rights reserved.