The invention relates to capsules comprising an encapsulated material and a capsule wall material, wherein the encapsulated material is a compound having a solubility in water of at most 10 g/l at 20°C and having a viscosity of at least 50 mPa s at a temperature of 20 °C measured at a shear rate of 300 s-1, and wherein the capsule wall material is the condensation product of silicon alkoxides having alkoxide groups and a polyalkylene oxide compound, and wherein the capsules have a d50 number average particles size in the range of 50 to 600 nm, and wherein the capsules are essentially free of surfactants.