Abstract Nanofluids have found crucial presence in heat transfer of applications with their promising characteristics that can be controlled as per requirements. In the present paper a critical review of Nanofluids has been carried out for the past two decades to design a new hybrid nanofluids for various engineering applications. Mono nanofluids, prepared with a single kind of nanoparticles, possess certain specific benefits owing to the properties of the suspended nanoparticle. However to further improve the characteristics of nanofluids, that could possess a number of favourable characteristics, researchers developed a new generation heat transfer fluid called hybrid nanofluid. Hybrid nanofluids are prepared either by dispersing dissimilar nanoparticles as individual constituents or by dispersing nanocomposite particles in the base fluid. Hybrid nanofluids may possess better thermal network and rheological properties due to synergistic effect. Hybrid nanofluids though having thermal performance properties but as a new type of working fluids, there are some challenges in their development. Firstly, there is lack of agreement between results obtained by different researchers; secondly, there is lack of theoretical model that can predict the exact behaviour of the hybrid nanofluids. Thirdly, in the preparation method, different methods lead to different result for a given nanofluid and volume fraction. Many researchers have used TiO2 & SiC as nano additives for increasing the performance of machining operation. In the present paper a new class of hybrid nano fluid i.e. SiC and TiO2 is proposed to study using proper combinations, necessity and benefits of implementing the performance of machining operations.