A process for the preparation of a core-shell microcapsule, said process comprising the steps of: 1) preparing an oligomeric composition comprising the reaction product of, or obtainable by reacting together: a) a polyamine component in the form of melamine or of a mixture of melamine and at least one C 1-4 compound comprising two NH 2 functional groups; b) an aldehyde component in the form of a mixture of glyoxal, a C 4-6 2,2-dialkoxy-ethanal and optionally a glyoxalate, said mixture having a molar ratio glyoxal/C 4-6 2,2-dialkoxy-ethanal comprised between 1/1 and 10/1; and c) a protic acid catalyst; 2) preparing an oil-in-water dispersion, wherein the droplet size is comprised between 1 and 600 μm, and comprising: i) an oil; ii) a water medium; iii) at least an oligomeric composition as obtained in step 1); iv) at least a cross-linker selected amongst: A) C 4 -C 12 aromatic or aliphatic di- or tri-isocyanates and their biurets, triurets, trimers and trimethylol propane-adduct; and/or B) a di- or tri-oxiran compounds of formula A-(oxiran-2-ylmethyl) n wherein n stands for 2 or 3 and A represents a C 2 -C 6 group optionally comprising from 2 to 6 nitrogen and/or oxygen atoms; v) optionally a C 1-4 compound comprising two NH 2 functional groups; 3) heating said dispersion; 4) cooling said dispersion; and 5) optionally drying the final dispersion to obtain the dried core-shell microcapsule. 1) preparing an oligomeric composition comprising the reaction product of, or obtainable by reacting together: a) a polyamine component in the form of melamine or of a mixture of melamine and at least one C 1-4 compound comprising two NH 2 functional groups; b) an aldehyde component in the form of a mixture of glyoxal, a C 4-6 2,2-dialkoxy-ethanal and optionally a glyoxalate, said mixture having a molar ratio glyoxal/C 4-6 2,2-dialkoxy-ethanal comprised between 1/1 and 10/1; and c) a protic acid catalyst; a) a polyamine component in the form of melamine or of a mixture of melamine and at least one C 1-4 compound comprising two NH 2 functional groups; b) an aldehyde component in the form of a mixture of glyoxal, a C 4-6 2,2-dialkoxy-ethanal and optionally a glyoxalate, said mixture having a molar ratio glyoxal/C 4-6 2,2-dialkoxy-ethanal comprised between 1/1 and 10/1; and c) a protic acid catalyst; 2) preparing an oil-in-water dispersion, wherein the droplet size is comprised between 1 and 600 μm, and comprising: i) an oil; ii) a water medium; iii) at least an oligomeric composition as obtained in step 1); iv) at least a cross-linker selected amongst: A) C 4 -C 12 aromatic or aliphatic di- or tri-isocyanates and their biurets, triurets, trimers and trimethylol propane-adduct; and/or B) a di- or tri-oxiran compounds of formula A-(oxiran-2-ylmethyl) n wherein n stands for 2 or 3 and A represents a C 2 -C 6 group optionally comprising from 2 to 6 nitrogen and/or oxygen atoms; v) optionally a C 1-4 compound comprising two NH 2 functional groups; i) an oil; ii) a water medium; iii) at least an oligomeric composition as obtained in step 1); iv) at least a cross-linker selected amongst: A) C 4 -C 12 aromatic or aliphatic di- or tri-isocyanates and their biurets, triurets, trimers and trimethylol propane-adduct; and/or B) a di- or tri-oxiran compounds of formula A-(oxiran-2-ylmethyl) n wherein n stands for 2 or 3 and A represents a C 2 -C 6 group optionally comprising from 2 to 6 nitrogen and/or oxygen atoms; A) C 4 -C 12 aromatic or aliphatic di- or tri-isocyanates and their biurets, triurets, trimers and trimethylol propane-adduct; and/or B) a di- or tri-oxiran compounds of formula A-(oxiran-2-ylmethyl) n wherein n stands for 2 or 3 and A represents a C 2 -C 6 group optionally comprising from 2 to 6 nitrogen and/or oxygen atoms; v) optionally a C 1-4 compound comprising two NH 2 functional groups; 3) heating said dispersion; 4) cooling said dispersion; and 5) optionally drying the final dispersion to obtain the dried core-shell microcapsule.