The adiabatic temperature displayed by the moving counterpart of Pohlhausen's classical plate thermometer is investigated as a function of the Prandtl number Pr. While in the classical case the heat release by viscous dissipation is due to the Blasius flow (of free stream velocity U0), in the present case it is due to the boundary-layer flow induced by a continuous plane surface moving with the uniform velocity U0 in a quiescent fluid (Sakiadis flow). It is found that the dimensionless adiabatic surface temperature (= recovery factor) in both cases is given by each a monotonically increasing function of Pr. The two functions take the same value 1 at Pr=1, but below and above of Pr=1, they deviate from each other significantly. The recovery factor of the moving plate thermometer is investigated analytically and numerically by using the series solution of the problem obtained by the Merkin transformation method.