Résumé : A study has been made of K--meson interactions at rest in the CERN 1.1 m3 heavy-liquid bubble chamber filled with a mixture of hydrocarbons. The emission frequency of Λ0-hyperons following K--meson absorptions in carbon nuclei is determined to be 0.68 ± 0.02. A detailed study of the (Λ0π-) final state has allowed an estimate to be made of the internal-conversion probability C(Σ+) of {perspective}+-hyperons produced in association with π--mesons. The result is C(Σ+)=0.62 ± 0.02. The contribution of the direct channel to the (Λ0π-) final state is found to be 0.23 ± 0.01. The results are compared with those obtained for other absorbing media. © 1977 Società Italiana di Fisica.