A cold-cathode Bayard-Alpert (BA) ionization gauge based on a carbon-nanotube (CNT) cold cathode has been fabricated. The linear CNT cathode was prepared by growing CNTS on a stainless-steel rod using thermal chemical vapor deposition. The gauge was tested at different pressure ranges and good linearity between the collected ion current and pressure was obtained. The sensitivity of the ionization gauge was tested and was about 3.6 Torr(-1) when the pressure ranged from 3 x 10(-5) to 3 x 10(-6) Torr. The methods for further improving the performance of the cold-cathode ionization gauge are discussed. (c) 2007 American Vacuum Society.