In the late eighties, a consortium of German companies called IK-CAPE developed a specification of routines to calculate thermophysical properties in FORTRAN. An implementation according to this specification was also developed and used in several in-house simulation codes and academic research projects. In a joint project with Bayer Technology Services, AixCAPE has equipped this IK-CAPE package with a CAPE-OPEN thermodynamic interface to permit the use of the existing property data input files in state-of-the-art simulation environments. Successful tests have been made with Aspen Plus, Pro/II, COCO, gPROMS, and Simulis Thermodynamics.