Thomson scattering (TS) experiments have been made on a low pressure surfatron induced plasma. TS is an active diagnostic method and the experimental results are directly related to important plasma properties such as the electron density, n_e, and the electron temperature, T_e. Therefore, the TS results for n_e and T_e can be used to calibrate passive diagnostic methods which are often based on plasma models. However, to apply TS on a surfatron induced plasma inside a quartz tube is experimentally demanding because of the large amount of stray light and a low intensity of the TS signal. To achieve low detection limits and high stray light rejection, a triple grating spectrograph was used in the detection branch and an iCCD was used to record the TS spectrum. For a typical plasma condition with an argon pressure of 10 mbar and an absorbed power of 50 W, the measured electron density was found to be equal to n_e ≈ 4 × 10¹⁹ m⁻³ and the electron temperature T_e ≈ 1.2 eV. In addition, frame-averaged results for 6, 10, 15 and 20 mbar argon plasmas for absorbed microwave powers in between 25 ⩽ P_ab ⩽ 60 W are presented. The trends found in the dependence of the pressure and power density are according to theory.