The pressure dependence of the Curie temperature T-C(P) in La0.75Ca0.25MnO3 was determined by neutron diffraction up to 8 GPa, and compared with the metallization temperature T-IM(P) (Postorino et al 2003 Phys. Rev. Lett. 91 175501). The behavior of the two temperatures appears similar over the whole pressure range, suggesting a key role of magnetic double-exchange also in the pressure regime where the superexchange interaction is dominant. The coexistence of antiferromagnetic and ferromagnetic peaks at high pressure and low temperature indicates a phase separated regime which is well reproduced with a dynamical mean-field calculation for a simplified model. A new P-T phase diagram has been proposed on the basis of the whole set of experimental data. RI Capone, Massimo/A-7762-2008