Magnesia-spinel refractory bricks are widely used in rotary kilns since they offer a desirable combination of mechanical, chemical and thermal properties at elevated temperatures. Recent trends in energy-efficiency and reduction of carbon footprint have led refractory manufacturers to develop energy-saving refractory bricks. One possible way to decrease energy consumption is using an energy-saving brick in which the thermal conductivity is reduced by increased porosity. However, mechanical, chemical and thermal limitations of the rotary kilns should be considered in brick design since porosity will degrade relevant properties. In this study, novel basic refractory bricks with reduced thermal conductivity were developed to reduce kiln shell temperature and hence reduce energy consumption. Substances forming different pore structures and their influence on microstructure as well as physical, mechanical and thermal properties were investigated. A novel energy-saving basic refractory brick with reduced thermal conductivity by optimum porosity structure is developed without compromising the refractoriness as well as mechanical and thermal properties.