Tetrazolinonecarboxamides of formula I wherein Het is oxetan-3-yl, thietan-3-yl, tetrahydrofuran-3-yl, furan-3-yl, tetrahydrothiophen-3-yl, thiophen-3-yl, tetrahydro-2H-pyran-3-yl, tetrahydro-2H-thiopyran-3-yl, tetrahydro-2H-pyran-4-yl or tetrahydro-2H-thiopyran-4-yl, in each case with or without substitution; R1 is optionally substituted alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, phenyl, or 3- to 7-membered heterocyclyl; R2 is hydrogen, alkyl, haloalkyl, alkenyl, haloalkenyl, alkynyl, or is optionally substituted cycloalkyl, cycloalkylalkyl, phenyl, phenylalkyl, 3- to 7-membered heterocyclyl, or 3- to 7-membered heterocyclylalkyl, their preparation and herbicidal compositions comprising them.