An inlet diffuser for the fixed-bed reactor is disclosed. The inlet diffuser comprises a truncated cone adapted to receive a stream of gas-liquid mixture. The truncated cone includes at least one opening formed on a circumference of the truncated cone. Further, the inlet diffuser comprises a vertical baffle plate in each of the openings and at least one horizontal baffle coupled to the truncated cone to absorb momentum of the stream received by the truncated cone. Furthermore, it comprises a cylindrical chamber in fluid communication with the truncated cone and adapted to receive the stream from the truncated cone. The cylindrical chamber includes at least one slot to discharge the stream from the inlet diffuser and a splash plate is disposed at a bottom portion of the cylindrical chamber with apertures to discharge the stream from the inlet diffuser.