The present invention relates to a varistor material for a surge arrester with target switching field strength ranging from 250 to 400 V/mm comprising ZnO forming a ZnO phase and Bi expressed as Bi2O3 forming an intergranular bismuth oxide phase, said varistor material further comprising a spinel phase, characterized in that the amount of a pyrochlore phase comprised in the varistor material is such, that the ratio of the pyrochlore phase to the spinel phase is less than 0.15:1.