We present a study of antineutrino interactions in hydrogen obtained in a 138000-picture run at the BNL 7-ft bubble chamber. The antineutrino beam had an energy distribution that peaked at ~1.1 GeV. The cross section measured for charged-current interactions is σ(ν¯p-->μ++anything)=(0.32+/-0.08)×10-38×[Eν¯ (GeV)] cm2. The neutral-current cross section is σ(ν¯p-->ν¯pπ+π-)=5.5+4.4-2.6×10-40 cm2. The ratio of strangeness-changing to non-strangeness-changing charged currents is Rs=0.06+0.13-0.05. An upper limit determined for charm production is σc<3.8×10-40 cm2 at the 90% confidence level. From the momentum-transfer distribution we measure average Q2 for inelastic charged-current events with energy greater than 2 GeV, <Q2>=(0.10+/-0.03)[Eν¯ (GeV)]+(0.10+/-0.09) (GeV/c)2. Using a maximum-likelihood method we determine from the quasielastic events ν¯p-->μ+n an axial-vector mass MA=0.9+0.4-0.3 GeV/c2.