This paper evaluates the effectiveness of p-doping transparent single-walled carbon nanotube (SWNT) films via chemical treatment with HNO3 and SOCl2. Stability of the improvement in electrical conductivity after doping is investigated for different doping treatments as a function of exposure time to air and as a function of temperature. Doped films were found to have a greater than twofold increase in conductivity with sheet resistance values as low as 105 Ω sq−1 with an optical transmittance of 80% at 550 nm. However, doping enhancements demonstrated limited stability in air and under thermal loading. The application of a thin capping layer of PEDOT/PSS is shown to stabilize the improvements in conductivity, evidenced by sustained lower sheet resistance in both air and under thermal loading.