Electrical characterization has been carried out on electron irradiated InP grown by metal‐organic chemical‐vapor deposition (MOCVD) and liquid encapsulated Czochralski (LEC), throughI–V(–T),C–V, deep level transient spectroscopy (DLTS) and admittance spectroscopy measurements and the resistance to electron radiation for these two materials has been compared. It was found that MOCVD‐InP was more resistant to electron radiation than LEC‐InP, as demonstrated by the lower carrier removal rate and change of series resistance in the MOCVD‐InP diodes as a result of electron radiation. The introduction rates for the dominant hole defectsH3 andH4 and for additional electron defect states were found to be similar for both materials, but were insufficient to explain the degree of degradation of solar cell efficiency incurred by these known defects. A new defect,HD1, has been found to be responsible for the high carrier removal rate and the introduction of a large series resistance which accounts for the difference of radiation hardness between these two materials. The results again show that the dominant irradiation defects in InP are not the defectsH3 andH4 as is usually accepted, but the new found defectHD1, which was undetected by the DLTS technique. ©1995 American Institute of Physics.