Unidirectional magnesium aluminosilicate (MAS) glass-ceramic matrix/silicon carbide (SIC) fibre composites were produced, employing the slurry infiltration-hot pressing technique. The densification and crystallisation behaviour of the (P2O5, B2O3)-containing MAS glass-ceramic matrix was studied in depth. The major result of the matrix study was the construction of a two-dimensional hot pressing 'window' within which MAS/SiC composites were successfully processed. The 'window' dimensions, namely temperature and time, were shown to depend on each other.