Virtual-labs are useful tools for education in chemical process control. A novel approach to virtual-lab implementation using the Modelica language is presented. This approach has the following advantages. Firstly, existing Modelica models can be employed to develop virtual-labs. If new models need to be programmed, the use of Modelica reduces considerably the modeling effort. Secondly, as the complete virtual-lab is described in Modelica, virtual-lab developers don't need to use programming languages. Finally, virtual-labs can be easily distributed to the users, who don't need to install any additional software. The proposed approach is based on the application of a methodology for interactive model development, and two software tools: a free Modelica library, named Interactive (http://www.euclides.dia.uned.es/Interactive), and the Dymola modeling environment. Several virtuallabs have been implemented and successfully applied to education in chemical process control. The development of a virtual-lab based on a complex model of a double-pipe heat exchanger is discussed. (c) 2011 Elsevier Ltd. All rights reserved.