Photoluminescence (PL) of Hg1-xCdxTe-based (x ~ 0.5) structures grown with molecular-beam epitaxy on GaAs and Si substrates was studied. The studied structures appeared to have substantial compositional fluctuations, which at low temperatures (T < 200 K) strongly affected the value of "optical" bandgap obtained in the experiment. Comparison of the experimental results with the data available in the literature showed that such fluctuations were in general typical of Hg1-xCdxTe with x ~ 0.5 fabricated with various technologies. At T > 200 K the effect of the fluctuations on the optical properties of the studied material became negligible, which confirmed that the structures were suitable for fabrication of photo-electronic devices operating in the extended short-wave infrared range.