Experimental results on the growth and velocity of droplets (up to 0.45 mm/s) during the temperature-induced phase separation of the 3-methoxypropionitrile/water solvent system as well as a variety of theoretical methods used to study the demixing dynamics are presented. Due to computational costs, the simulation with Molecular Dynamics (M D) is feasible only for very short times (ps) and miniscule boxes (A). Dissipative Particle Dynamics (DPD), where a coarse-grained model of the system is employed, allows nanosecond simulations in a box with more than 13 million atoms in a diffusion-dominated regime. Finally, the influence of the diffusion/convection ratio during the separation in the mu s scale is studied by use of a code based on Model H for both instantaneous and non-instantaneous quenching cases. Structural information and macroscopic parameters, such as interfacial tension, can be derived from the molecular simulations.