Direct current (DC) current-voltage (I-V) characteristics of silicone rubber filled with conductive carbon black (CB) were studied at room temperature in the voltage range of 1-46 V. The current-voltage relationship can be expressed as I = AV(B) where A and B are constants that show capability and property of electrical conduction, respectively. The I-V curve can be divided into ohmic and nonohmic regions. In nonohmic region, B < 1, and the resistance increases with the rise of voltage. Higher CB loading leads to lower transforming voltage from ohmic to nonohmic region and much deviation from Ohm's law. The reason for this deviation is the unbalance between the heat generated and the heat loss of conductive silicone rubber during the measurement. When the heat effect is eliminated completely, the electrical conduction is ohmic. (C) 2004 Wiley Periodicals, Inc.