Boron carbide (B4C) ceramics were produced by spark plasma sintering technique with 5, 10, 15, and 20 vol.% aluminum (Al) in order to improve sintering behaviours of B4C ceramics. B4C ceramics were produced, having square cross-section and 50x50x5 mm(3) dimensions. The sintering process was carried out at different temperatures by applying 40 MPa of pressure with 100 degrees C/min under vacuum. The effects of various amounts of Al additive and sintering temperature on density, vickers hardness, fracture toughness and microstructure were examined. The hardness and fracture toughness of the samples were evaluated by the Vickers indentation technique. Microstructures of the samples were characterized by scanning electron microscopy technique. Fast neutron attenuation properties of the ceramics having highest density were also investigated.