  We discuss the phenomenology of colour scalar octets. Namely, we consider the
discovery potential of scalar octets at LEP, FNAL and LHC. Scalar octets decay
mainly into two gluons and new hadrons composed from scalar colour octets are
rather long lived $(\Gamma \leq O(10)Kev)$. For the scalar octet masses $M \geq
O(50)Gev$ scalar octets producing at FNAL or LHC decay into two gluons that
leads to additional four-jet events. We propose to look for scalar octets by
the measurement of the distributions of differential cross sections on the
invariant di-jet masses. Scalar octets naturally arise in models with
compactification of additional space dimensions. In such models the branching
ratio for the scalar octet bound state into two photons is $O(10^{-2})$ that
leads to the events with two photons and two jets. We also point out that the
current experimental data don't contradict to the existence of light ($M \sim
O(1)Gev$) scalar octets. Light scalar octets give additional contribution into
QCD $\beta$-function and allow to improve the agreement between deep inelastic
and LEP data.
