A CW tunable $10.6\mathrm{\mu m}$ ${\mathrm{CO}}_2$ laser differential absorption lidar (DIAL) system has been developed, for the first time to our knowledge, for the remote sensing of triacetone triperoxide (TATP) gas vapors, which have strong absorption lines at several wavelengths, including 3.3, 8.3, and $10.6\mathrm{\mu m}$ . The DIAL laser beam was transmitted through an enclosed absorption cell containing TATP or ${\mathrm{SF}}_6$ , and backscattered returns were measured from a retroreflector array target at ranges of $5–100\mathrm{m}$ . DIAL sensitivity for the detection of TATP was about $0.5\mathrm{ng}/\mathrm{\mu l}$ [ $52\mathrm{parts}\mathrm{in}{10}^6(\mathrm{ppm})$ ] for a $0.3\mathrm{m}$ path.