An effective way to solve the issue of global warming is reduction of CO₂ emissions through its capture from stationary sources of energy production. A large amount can be stored in depleted oil and gas reservoirs being mixed with impurities and hydrocarbons in states close to the critical point. Thermodiffusion may result in accumulation of chemically active impurities near the bottom of the cap rock, thus leading to provoke leakages. The objective of the KIBILI project aims to study the kinetic of the mass transport in a binary mixture in the gas/liquid critical region. The measurements of diffusion and Soret coefficients are foreseen to be carried out in a CO₂–hydrocarbon system, which could be representative of those mixtures stored in depleted oil and gas reservoirs. The microgravity conditions provided by nano-satellites of the project QB50 would be a very nice opportunity to realize accurate measurements of these delicate phenomena.