Abstract: Microcapsules useful for producing pressure-sensitive recording materials are obtainable by polymerizingA) 30-100% by weight of one or more C.sub.1 -C.sub.24 -alkyl esters of acrylic or methacrylic acid (monomers I),B) 0-80% by weight of a bi- or polyfunctional monomer (monomer II) which is soluble in a solvent which is insoluble or only sparingly soluble in water, andC) 0-40% by weight of other monomers (monomers III),the solvent being present alone or together with the monomers and a free radical initiator as the disperse phase of a stable oil-in-water emulsion and the polymerization being initiated and controlled by the thermal decomposition of the free radical initiator.