The value for surface diffusivity of Zr tetragonal ZrO2-3mol % Y2O3 has been calculated from measurements of surface area reduction and pore growth in powder compacts during sintering. The surface diffusivity thereby obtained can be described by D-s,D- Zr+4 = 5.52 x 10(5) exp[-531(kJ mol(-1))/RT] m(2)/s, which is in reasonable agreement with values calculated by prior researchers from direct TEM observation of neck growth between touching particles.