Depositing approximate to0.5 monolayer of Cs on a properly prepared disk of oxygen free high conductivity (OFHC) copper. the workfunction decreases by 3.17 +/- 0.15 eV. As a result, the coefficient of secondary electron emission under electron bombardment increases and the width of the secondary electron energy distribution at half maximum decreases from 6.7 to 2.8 eV. For an impact energy of the: primary electrons E-p < 20 eV, it is found that the production of true secondary electrons increases by a factor 2.2. The probability of elastic scattering of very low energy electrons increases from 0.1 on clean copper to 0.4 on cesiated copper.