Structure data for both triclinic alpha- and gamma-CuMoO4 have been de
livered with anisotropic temperature factors at 190 K. The complete te
nsors of linear thermal expansion coefficients were derived for alpha-
and gamma-CuMoO4 using the temperature dependence of lattice paramete
rs within the temperature range 20 K-300 K and 20 K-260 K, respectivel
y. The orientation of principal axes and values of principal expansion
coefficients are given for selected temperatures. Their relation to t
he structure is discussed. The volume expansion coefficient of a CuMoO
4 becomes negative below 80 K.