We report on the magnetic susceptibility and electron spin resonance
measurements on polycrystalline samples of the vanadium oxide
VOSb2O4, a quasi-one dimensional S=1/2 Heisenberg system. We show
that the susceptibility vanishes at zero temperature, as in a gapped system,
and we argue that this is due to a spin-Peierls transition with strong
structural fluctuations.Comment: 5 pages, 4 figure