The magnetic and transport behaviors of cerium substituted iron oxy-arsenide superconductor with x = 0.1 to 0.4 fluoride (F) doping have been investigated in this report. Temperature dependent susceptibility and resistivity measurements show the 0.1 F-doped sample (CeFeAsO 0.9 F 0.1 ) has a superconducting transition temperature ( T c ) at around 30 K. With increasing doping to x = 0.2 and beyond, T c is observed to have saturated at around 40 K. Temperature dependent susceptibility measured in different magnetic fields for the under-doped sample shows Meissner effect in low fields and the diamagnetism is still visible up to 1 Tesla. Furthermore, there is also an obvious magnetic transition below 5 K, perhaps originating from the magnetic ordering of the rare-earth cerium. The corresponding resistance versus temperature measurements in different magnetic fields indicate a broadening of less than 3 K for T c at mid-point by increasing the field from 0 to 5 Tesla, indicating a rather low anisotropy. An esti...