The voltammetry of the clean (1 x 1) and reconstructed hex-R0.7 degrees phases of Pt{100} prepared in UHV are reported. By comparison with the UHV data, both phases may readily be prepared using a flame-annealing procedure so long as the conditions of sample cooling are precisely controlled. The well-ordered (1 x 1) phase may be formed by cooling in hydrogen. Back transfer to UHV of the hydrogen-cooled sample gave rise to a p(1 x 1) LEED pattern. These findings are in accordance with previous investigations [Attard and Price, Surf. Sci. 335 (1995) 63 and erratum; Al-Akl et al., J. Chem. Soc. Faraday Trans. 91 (1995) 3585; Sashikata et al., Langmuir 14 (1998) 2896; Tidswell et al., Phys. Rev. Lett. 71 (1993) 1601]. The voltammetry of the UHV-prepared hex-R0.7 degrees phase can be obtained only after a flame-anneal treatment by cooling rapidly in a flow of inert gas such as argon in which oxygen has been rigorously excluded. In contrast to the hydrogen cooled Pt{100} electrode, subsequent LEED analysis of the argon cooled sample showed a reconstruction pattern similar, though not identical to one reported recently by Zei et al. for a partially deconstructed Pt{100} electrode. On the basis of these results it is suggested that the p(1 x 1) and hex-R0.7 degrees phases of Pt{100} may be prepared under ambient conditions in an electrochemical cell. Although the potentials at which the reconstructed phase is stable are different from those reported by Zei and co-workers, the data do support their earlier results showing that the reconstructed phase of Pt{100} is stable when in contact with electrolyte solutions.