The invention provides phenol ethers of the formula: ##STR1## wherein R is branched C.sub.3-4 alkyl, C.sub.3-4 cycloalkyl, branched cyano(C.sub.3-4 alkyl), phenyl(C.sub.2-3 alkyl), halophenyl(C.sub.2-3 alkyl), (C.sub.1-4 alkoxy)phenyl(C.sub.2-4 alkyl), or (C.sub.1-4 acyl)amino(C.sub.1-4 alkyl), alk is C.sub.1-4 alkyl substituted by a 3 to 6 membered cycloalkyl group, X is --O--, --S-- or --SO.sub.2 --; and R.sub.1 is --C.sub.1-4 alkyl- or --C.sub.1-4 alkoxy-, in their racemic and optically active forms, and their addition salts with pharmaceutically acceptable acids. These compounds are useful in therapy as .beta.-adrenergic blocking agents. Intermediates are also provided.