A series of CuxMg1–xNb2O6 (x = 0, 0.2, 0.4, 0.6, 0.8, 1) columbites were prepared using the sol-gel technique. The samples were sintered at 900 °C for 6 h. The prepared samples were structurally characterized using X-ray diffraction (XRD) method. To study their applicability in low temperature cofired ceramic (LTCC) technology, elastic properties have been characterized for mechanical compatibility. Elastic behavior was investigated at 300K, employing ultrasonic pulse-transmission technique at 1 MHz. The values of elastic moduli and acoustic Debye temperature (µD) were computed from longitudinal and shear velocities. The measured values were corrected to zero porosity using Hasselman and Fulrath's formula. The elastic constants of the samples, estimated using Modi's heterogeneous metal-mixture rule, were also reported. The variation of elastic moduli was interpreted in terms of strength of interatomic bonding. Microstructure of these samples was studied using the FESEM (field emission scanning electron microscopy) technique. Mechanical properties including yield strength, tensile strength and thermal stress resistance were calculated from thermal properties measured through thermal conductivity and thermal expansion coefficient.