The half-life of 210Pb has been calculated from measurements of the specific activity and the 210Pb-concentration of a 210Pb-solution. The specific 210Pb-activity was determined by measuring the daughter product 210Po using an α-spectrometric isotope dilution method with 208Po as tracer. The 210Pb-concentration was measured by mass-spectrometric isotope dilution analysis. A half-life of 22.26 ± 0.22 ( = 2 σ) years has been obtained.