Monotectic alloys with stable or metastable miscibility gap are in focus of basic and applied research in a view of design of new metal matrix composites. Due to combination of the distinctive, often opposing, characteristics of coexisting either amorphous or crystalline solid phases, materials with exceptional mechanical, magnetic, or other properties can be obtained. For the control of solidification and microstructure development in the alloys with liquid-liquid miscibility gap, knowledge of their thermophysical properties is a key issue. Because of the high melting temperatures, chemical aggressiveness against crucibles, high oxygen affinity etc., experimental investigations of the metallic monotectic alloys is a challenging task. With some examples, we will show how the thermophysical properties such as interfacial tension, wetting, density, characteristic temperatures of the phase transformations can be measured by applying different experimental techniques. Also we will demonstrate how the microstructure of the solid monotectic alloys depends on the solidification (casting) conditions.