The d.c. conductivity (sigma) of (a) glasses prepared by the press-quenching method and (b) glass-ceramics (crystallized glass) produced by post-heat treatment was investigated in the system Sb2O3-Ca O-V2O5 and their conduction mechanism was studied. The glasses were n-type semiconductors with sigma = 2.6 x 10(-6) similar to 2.8 x 10(-5) S cm(-1) at 333 K for varying glass compositions. The conduction was attributed to small polaron hopping in the adiabatic regime. The estimated carrier density was 1.7 similar to 3.8 x 10(21) cm(-3) for V2O5 = 70 similar to 80 mol % and the mobility was 3.5 x 10(-9) to 6.9 x 10(-8) cm(2) V-1 s(-1). Crystallization raised the conductivity by a factor of 10(3). The crystalline product in the glass-ceramics was Ca0.17V2O5. The glass-ceramics were n-type semiconductors, and the conduction was interpreted by a superposition of the small polaron hopping in the crystalline and glassy phases.