Spectrum of R Mon obtained with the UVES spectrograph on the ESO/VLT. In the middle and bottom panels, synthetic photospheric Kurucz models with temperatures 11 000, 20 000, 25 000, 30 000 K are plotted in green, red, blue, and cyan, respectively. Assuming that the absorption features in the blue side of Hϵ, Hδ, and Hγ have a substantial photospheric contribution, the comparison with the observations suggests that R Mon is an early B-type star with an effective temperature between 20 000 and 30 000 K.