Diffusion data in multicomponent liquids are scarce, because these diffusion measurements are time-consuming and laborious. Most diffusion data are therefore available for binary mixtures. While there are at least some data on ternary diffusion, the data on quaternary diffusion are very limited. Therefore, experimental data on multicomponent diffusion are the bottleneck for modeling and understanding mass transport in chemical, biological, and physiological multicomponent systems. In this work, we present the first measurement of quaternary diffusion coefficients using Raman microspectroscopy in a H-cell microchannel. This measurement method provides access to quaternary diffusion coefficients even from a single experiment. Three experiments are sufficient for good precision and low uncertainty. The presented measurement method reduces the experiment time, the sample volume, and the number of experiments. Diffusion coefficients are reported for the quaternary system cyclohexane + toluene + acetone + methanol and its ternary subsystem cyclohexane + toluene + methanol at 298.15 K. For both systems, significant cross-diffusion coefficients were observed even at low concentrations. Despite the molecular interactions, adding acetone as further component to the system reduced the cross-diffusion coefficients by almost 1 order of magnitude showing the complex behavior of multicomponent diffusion.