In-stream technology (hydrokinetic technology) is a newly emerging renewable energy generation technology. The technology utilizes the kinetic energy of flowing water without constructing a dam/barrage/weir. In the present study, a review of the techno-economic analysis of hydrokinetic technology has been presented. The technical part covers the total energy generation that includes site characterization, device selection and optimization, and its application. The financial part covers the cost of energy generation/kw. It is found that the power generation cost from a single unit is very high and, thus, not financially viable. Therefore, the study suggests increasing the number of turbine units to reduce the cost of energy generation. It is necessary to determine the wake recovery distance for the deployment of 2nd turbine, which results into 25D for the Savonius turbine, 4D for the helical Savonius turbine, 3D-4D for the tidal stream turbine, 6D for the propeller turbine, and 12D for the horizontal axis turbine where D is the the turbine diameter. The levelized cost of energy for 100 units of turbines is reduced by almost 87% compared to a single unit. The article will insight the researchers and industrialists for improving the design, performance, and commercializing the technology.