  The high-frequency peaked BL Lac PG 1553+113 was observed in 2005 with the
H.E.S.S. stereoscopic array of imaging atmospheric-Cherenkov telescopes in
Namibia. Using the H.E.S.S. standard analysis, an excess was measured at the
4.0 sigma level in these observations (7.6 hours live time). Three alternative,
lower-threshold analyses yield >5 sigma excesses. The observed integral flux
above 200 GeV is (4.8 +/- 1.3_{stat} +/- 1.0_{syst}) x10^{-12} cm^{-2} s^{-1},
and shows no evidence for variability. The measured energy spectrum is
characterized by a very soft power law (photon index of Gamma=4.0 +/- 0.6).
Although the redshift of PG 1553+113 is unknown, there are strong indications
that it is greater than z=0.25 and possibly larger than z=0.78. The observed
spectrum is interpreted in the context of VHE gamma-ray absorption by the
Extragalactic Background Light, and is used to place an upper limit on the
redshift of z<0.74.
