An x‐ray photoelectron spectroscopy (ESCA) apparatus designed specifically for surface research is described. The features, included in one vacuum envelope, are ultrahigh vacuum, a high intensity x‐ray source, a 10 cm mean radius hemispherical electron energy analyzer, sample cleaning by argon ion bombardment, sample heating by electron bombardment, and the facility for the collection of electron spectra as a function of angle relative to the surface plane of the sample. It is shown that (1) sample cleaning increases net signal strengths by factors as great as 14; (2) less than 2% of a monolayer of cesium on a clean molybdenum substrate can be readily detected; and (3) that ultrahigh vacuum is essential for investigation of well‐defined surfaces. Surface sensitivity is increased by an order of magnitude when spectra are collected at low electron take‐off angles relative to the surface plane, and the importance of measuring angular dependence of spectra for interpretation of data from surfaces is demonstrated.