Crosslinkable, semiconductive, peroxide-free thermoplastic compositions having a stable volume resistivity of less than 1000 ohm-cm comprise, based on the weight of the composition: A. 60-90 wt % silane-functionalized polyethylene; B. 0.5-20 wt % organopolysiloxane containing two or more functional end groups; C. 10-20 wt % high conductivity carbon black, e.g., a carbon black having an average particle size of 50 nm or less, a surface area (BET) of 700-1250 m2/g, and an oil absorption (DBP) of 300-500 ml/100 g; and D. 0.05-0.2 wt % crosslinking catalyst.