One-prong τ decays into final states involving kaons are studied with about 161 000 τ+τ− events collected by the ALEPH detector from 1991 to 1995. Charged kaons are identified by dE/dx measurement, while K0L 's are detected through their interaction in calorimeters. Branching ratios are measured for the inclusive mode, B(τ−→K−Xντ)=(1.52±0.04±0.04)% , where X can be any system of neutral particles, and for the exclusive modes B(τ−→K−ντ)=(6.96±0.25±0.14)×10−3,B(τ−→K−π0ντ)=(4.44±0.26±0.24)×10−3,B(τ−→K−π0π0ντ)=(0.56±0.20±0.15)×10−3,B(τ−→K−π0π0π0ντ)=(0.37±0.21±0.11)×10−3,B(τ−→K−K0ντ)=(1.62±0.21±0.11)×10−3,B(τ−→K−K0π0ντ)=(1.43±0.25±0.15)×10−3,B(τ−→K0¯¯¯¯¯π−ντ)=(9.28±0.45±0.34)×10−3,B(τ−→K0¯¯¯¯¯π−π0ντ)=(3.47±0.53±0.37)×10−3, where the first error is statistical and the second is systematical. Upper limits for B(τ−→K0¯¯¯¯¯π−π0π0ντ) and B(τ−→K−K0π0π0ντ) are also obtained. Mass spectra in the final states are investigated in order to study the relevant dynamics.