A hydraulic brake piston (11) is formed of a clay based ceramic or conventional ceramic material, such as a kaolin based ceramic with a low thermal conductivity. The piston (11) may be incorporated in a disc brake assembly comprising a caliper body (10) provided with a cylinder which receives the piston (11). Hydraulic brake fluid is introduced under pressure into the space (12) within the body (10) to displace the piston from the body and into contact with a disc pad (14). The ceramic piston retards heat transfer from the disc pad into the brake fluid thus reducing the cause for vapour lock.