NbC containing ceramic composites were manufactured from poly( siloxane)/Nb/NbC filler mixtures by a high temperature reaction bonding process. During heating in an inert atmosphere the Si-O-C ceramic residue of the polymer reacted with the metallic Nb filler to form NbxSiy, NbO and NbC. Samples with a high Nb/NbC ratio showed reduced porosity and increased hardness after pyrolysis at 1200degreesC. (C) 2003 Kluwer Academic Publishers.