Partially crystalline precursor derived Si-B-C-N ceramics were investigated at elevated temperatures by compression creep experiments. Load change and constant load experiments at various temperatures in the range of 1300-1500 °C yield viscosity data as high as 1015-1016 Pa s and the values were determined assuming Newtonian flow. The anelastic behavior was analyzed with the help of Kohlrausch-Williams-Watts equation (KWW) and the fitting parameters are used to describe the relaxation behavior of this family of materials. © 2006 Elsevier Ltd. All rights reserved.