The electronic polarizabilities of most cations, such as Na+, Ca2+, Fe2+, Fe3+, and Zr4+, show a monotonic decrease as the cation coordination increases. However, polarizabilities of the ions Ti4+, V5+, and V5+ show strong deviations from a regular decrease. In this paper we characterize the Ti and vanadyl compounds by infrared frequencies, by the short Ti4+– O, V4+–O, V4+–O, V5+–O, and V5+–O bonds and the polarizabilities of Ti4+, V4+, V4+, V5+, and V5+ determined from refractive index measurements. Analysis of the structures of 18 compounds containing short Ti–O bonds supports the concept of the short Ti–O bond being associated with the bond valence sum (omitting Ti) around the oxygen atom O*. The short Ti–O* bond occurs to satisfy the bond valence requirement of (O2–) of ∼2.0 vu. Plotting the Ti–O* distances of 18 minerals versus the bond valence sum (BVS) around O* shows an approximately linear relationship. Extrapolation to BVS = 0 yields a minimum distance of 1.65 Å. The mean value is 1.693 Å. The mean short distances in V4+ vanadyl minerals are 1.597 Å (CN = 5) and 1.590 Å (CN = 6), whereas the mean short distance in five V5+ minerals is 1.647 Å (CN = 5) and in 14 V5+ minerals is 1.644 Å (CN = 6). We compare the polarizabilities of Ti and [5,6]V4+ and [5,6]V5+ ions with the polarizabilities of -coordinated Ti4+ (Ti4+ ) and -coordinated Ti4+ (Ti4+ ) and of -, -, and -coordinated V4+ and V5+ ([n]V4+ and [n]V5+) and hypothesize that the reduced polarizability of Ti4+, V5+, and V5+ ions is caused by the short Ti–O* and V=O bonds.