The monograph investigates the concept of technical theory and formation of theoretical knowledge in technical science. Peculiarities of theory in modern technical science are studied. Technical idea is considered as a starting point for the formation of theoretical knowledge. The formation of theory during the period of justification of technical idea is investigated. The analysis of formation of theoretical knowledge in the period of development of technical object is carried out. Concrete examples of theory formation in radio electronics: radio engineering and solid-state nano- and microelectronics are given. For researchers, scientists and technicians engaged in the study of philosophy of science, research, development and application of photodetectors, emitters, video processors, radio engineering, nano- and microelectronic devices and devices.