Abstarct: In this research, the process of fabrication a gas sensor using a mextallic-semiconductor-mextal junctions that contains Ti and Au gold and carbon nanotubes vertically aligned (VACNT), which is characterized by a chemical deposition reaction laxyer with a plasma enhanced with nickel Ni catalyst at a distance The gap between two mextal electrode grown in size of 80 micrometers and 4 mm2 has been developed and used to detect toxic gases. In experiments of various concentrations ranging from 500 to 1500 ppm, three NO2, N2 gas and acetone gas were injected into the sensor in a room temperature room without heating, and changes in the electric current of the sensor were measured at a constant voltage of 2 volts and then, according to the changes Sensor resistance is calculated and shown for each gas and the sensor sensitivity changes. For concentrations of 1500 ppm, three gases of NO2, N2 and acetone to gastric juice have a sensitivity of 13%, 33% and 6.5%.