Résumé : The purpose of this experiment, entitled Chemical Waves in Soret Effect (CWIS), is to visualize the chemical wave induced by the thermodiffusion of a binary liquid mixture. The chemical wave is a concentration front that rapidly propagates from the thermal boundaries of the liquid mixture, and which marks the beginning of the chemical sorting phenomenon called thermodiffusion, induced by an imposed thermal gradient. In order to eliminate the contribution of buoyancy and bulk convective fluid motion, this experiment takes advantage of the several minutes of milligravity provided by an Improved Orion sounding rocket, as a part of the REXUS 16 launch campaign. The launch vehicle will fly to an altitude of nearly 100km, with a number of experiments on-board, ending with an atmospheric re-entry and parachute recovery of the experimental modules. The REXUS/BEXUS programme is realised under a bilateral Agency Agreement between the German Aerospace Centre (DLR) and the Swedish National Space Board (SNSB). This team's experimental module, currently under development, uses a Fizeau interferometer to study the chemical wave in a small-volume mixture of water and ethylene glycol, taking advantage of the difference in the refractive indices of these two fluids, and the time-dependent nature of the thermodiffusion process. This paper presents the chemical, electrical, mechanical, and thermal systems being developed for this unique application. A particular focus in this paper is the Finite Element Analysis (FEA) of the payload, required to maximally isolate the payload from the rocket's vibrations, but the other systems are presented in some depth also. Finally, this paper will present some of the qualification tests for the hardware and software, conducted with the guidance of the European Space Agency, and on a pre-defined timeline dating back to original project proposal in mid-2012. ©2013 by the International Astronautical Federation. All rights reserved.