Subpicosecond electrical pulses were generated and characterized in slotlines fabricated on LT-GaAs substrate for the first time, in our knowledge, by using femtosecond photoconductive correlation techniques. The measured pulse width is 0. 7ps at the generation site. The velocity of the pulses propagating in the slotlines is 1/2.3 of the light velocity in vacuum and the estimated attenuation coefficient of the electrical pulses is 20dB/mm. The pulse is broadened to 2.86ps after propagating distance of 420 along the slotlines. The measured parameters are consistent with the predicted values.