  Hadron electromagnetic form factor in the time-like region at the boundary of
the physical region is considered. The energy behavior of the form factor is
shown to be determined by the strong hadron-antihadron interaction. Imaginary
parts of the scattering lengths for $p\bar{p}$, $\Lambda\bar{\Lambda}$,
$\Lambda\bar{\Sigma}^0 (\bar{\Lambda}{\Sigma}^0)$ and
${\Sigma}^0\bar{\Sigma}^0$ are estimated. Developed approach enables us to
estimate imaginary part of the scattering volume from $D^*\bar{D^*}$
experimental data. The form factor energy behavior away from the threshold is
obtained within a semiphenomenological model of hadron-antihadron interaction.
