  Superconducting Pr$_2$CuO$_x$, $x\simeq 4$ (PCO) films with $T^\prime$
structure and a $T_c$ of 27 K have been investigated by various optical methods
in a wide frequency (7 - 55000 cm$^{-1}$) and temperature (2 to 300 K) range.
The optical spectra do not reveal any indication of a normal-state gap
formation. A Drude-like peak centered at zero frequency dominates the optical
conductivity below 150 K. At higher temperatures, it shifts to finite
frequencies. The detailed analysis of the low-frequency conductivity reveals
that the Drude peak and a far-infrared (FIR) peak centered at about 300
cm$^{-1}$ persist at all temperatures. The FIR-peak spectral weight is found to
grow at the expense of the Drude spectral weight with increasing temperature.
The temperature dependence of the penetration depth follows a behavior typical
for $d$-wave superconductors. The absolute value of the penetration depth for
zero temperature is 1.6 $\mu$m, indicating a rather low density of the
superconducting condensate.
