Ceramic cores for high-pressure turbine blade manufacturing are characterised by highly complex shapes possessing long thin grooves and many small diameter holes. The cores in the experiments have been produced via injection moulding, which required selecting a thermoplasticiser and determining the optimal processing conditions. The effect of different additives (borosilicate glass, alumina and zirconium silicate) on the properties of silica-based ceramic cores was analysed. The post-shaping process of cores included water and thermal debinding, sintering, precision machining, and dimension measurements. The newly-designed material for cores manufacturing comprises 64 wt% quartz glass, 13 wt% zirconium silicate, 12 wt% alumina and 11 wt% borosilicate glass, fulfils rigorous requirements concerning mechanical properties and dimensional accuracy. The strength is equal to 25.8 MPa, surface roughness 2.3 μm, shrinkage below 1.9% and mean pore diameter of 4.8 μm. The manufactured cores were positively verified during high-pressure turbine blade casting made of Ni-based superalloys in industrial conditions.