We have used an ultrahigh vacuum variable-temperature scanning tunneling microscope to study in situ Na intercalation in 1T-VSe2. At room temperature the clean surface showed large flat areas and a trigonal atomic arrangement. Tunneling spectroscopy revealed the known state at 100 mV below E-F. At 60 K the clean surface showed a 4 x 4 charge density wave and the spectra showed a CDW gap Delta approximate to 80 mV. When evaporating less than or equal to 1 ML Na at room temperature, the intercalated Na were distributed non-uniformly, giving bright areas of increased topographic height where Na was intercalated. In the intercalated material the VSe2 state was seen in the tunneling spectra, and was slightly shifted towards E-F. Preliminary spectroscopy of the intercalated material at 60 K showed two different types of spectra. One type showed the VSe2 peak clearly, but had no sign of the CDW gap, while the other type showed a gap structure but did not resolve the VSe2 state. Presently, we can not tell whether these different spectra originate from the differences in the intercalated and non-intercalated areas or not.