  The discovery of high-temperature superconductivity in compressed H3S by
Drozdov and co-workers (A. Drozdov, et. al., Nature 525, 73 (2015)) heralded a
new era in superconductivity. To date, the record transition temperature of Tc
= 260 K stands with another hydrogen-rich compound, LaH10 (M. Somayazulu, et.
al., arXiv:1808.07695) which becomes superconducting at pressure of P = 190
GPa. Despite very intensive first-principle theoretical studies of
hydrogen-rich compounds compressed to megabar level pressure, there is a very
limited experimental dataset available for such materials. In this paper, we
analyze the upper critical field, Bc2(T), data of highly compressed H3S
reported by Mozaffari and co-workers (S. Mozaffari, et. al., LA-UR-18-30460,
DOI: 10.2172/1481108) by utilizing four different models of Bc2(T). In result,
we find that the ratio of superconducting energy gap, {\Delta}(0), to the Fermi
energy, {\epsilon}F, in all considered scenarios is 0.03 <
{\Delta}(0)/{\epsilon}F < 0.07, with respective ratio of Tc to the Fermi
temperature, TF, 0.012 < Tc/TF < 0.039. These characterize H3S as
unconventional superconductor and places it on the same trend line in Tc versus
TF plot, where all unconventional superconductors located.
