Form a sample of about 75000 τ decays measured in the ALEPH detector, 1-prong charged kaon decays are identified by the dE/dx measurement in the central detector. The resulting branching ratios for the inclusive and exclusive modes are: B(τ --> ντK- >= 0π0 >= 0K0) = (1.60+/-0.07+/-0.12)%, B(τ --> ντK- = (0.64+/-0.05+/-0.05)%, B(τ --> ντ-π0 = (0.53+/-0.05+/-0.07)% and B(τ --> ντK-π0π0) = (0.04+/-0.03+/-0.02)%. Exclusive modes are corrected for measured KL0 production. The rate for τ --> ντK- agrees well with the prediction based on τ - μ universality.
