High entropy pyrochlores(HEP)are potential candidates as dispersoids in the oxide dispersed strength-ened steels or alloys,which can be used in nuclear reactors and supercritical boilers.For the first time,HEP oxides Y2(TiZrHfMoV)2O7 were synthesized with Y2Ti2O7 as a base structure with the B site(Ti)substituted with five cations through reverse co-precipitation technique in the nanocrystalline form at lowest synthesis temperature.The synthesis parameters for Y2(TiZrHfMoV)2O7(5C)and other derived compositions(five compositions of four cationic systems with each cation eliminated at B site from 5C)are optimised to obtain lower crystallite and particle sizes.5C has a smaller crystallite size(27 nm)than other single-phase compositions.The cation\'s influence,oxidation state,and oxygen vacancy in the phase formation were analysed through XPS.The single-phase HEPs are consolidated through spark plasma sin-tering.Y2(TiZrHfMo)2O7(4C-V)shows the highest hardness among the compositions reported so far due to its finer grain size,and Y2(TiHfMoV)2O7(4C-Zr)has a higher Young\'s modulus compared to other single-phase composition due to its higher degree of order in the structure.