New substituted triazolylmethyl tert.-butyl ketones of the formula ##STR1## in which R represents alkyl, alkenyl, alkynyl, optionally substituted cycloalkyl, optionally substituted cycloalkylalkyl or optionally substituted aralkyl,X represents hydrogen or halogen andY represents halogen,and the acid addition salts and metal salt complexes thereof, a process for the preparation of said novel compounds, their use as plant protection agents and as intermediate products for the synthesis of other plant protection agents.