The problems of using the hot-wire method for studying fluctuations in flows are considered when standard approaches and conventional modes cannot be used due to constraints caused either by the flow parameters or by the characteristics and conditions of the experiments. Examples of measurements under conditions of extremely low pressures and beyond the limits of the continuity of the medium in the CO2-laser are given; The use of data of hot-wire measurements for the determination of sources of disturbances in test sections of high-speed wind tunnels is shown; the design of a probe for measurement of concentration of components of the binary gas mixture is described, etc.