The invention relates to a process for the preparation of a semi-crystalline semi-aromatic polyamide copolymer (Co-PA) having a melting temperature (Tm-Co-PA) of at least 300° C., comprising steps of (a) preparing a first semi-crystalline semi-aromatic polyamide (A), having a melting temperature (Tm-A) of at least 310° C.; and consisting of repeat units derived from 45-50 mol % terephthalic acid; 47.5-50 mol % of diamine; and 0-5 mol % of one or more other amine and/or acid group containing components; the mol % being relative to the total molar amount of said amine and/or acid group containing components; and wherein poly-amide (A) is prepared by a process comprising direct solid-state polymerization of a diamine-dicarboxylic acid salt of the terephthalic acid and the diamine; (b) providing a polyamide (B), being an amorphous polyamide having a glass transition temperature (Tg-B) below Tm-A, or a second semi-crystalline polyamide having a melting temperature (Tm-B) below Tm-A, or a combination of the amorphous polyamide and the second semi-crystalline polyamide; (c) heating and melt-mixing polyamide (A) and polyamide (B), thereby obtaining a miscible polymer melt with a temperature (T-melt) above Tm-A; and (d) cooling the melt to a temperature below the solidification temperature of the melt, thereby obtaining a solid semi-crystalline semi-aromatic polyamide copolymer.