The herbicidally active substituted N-carbamoyl-tetrazolinones of the formula (I) ##STR1## in which R.sup.1 represents, inter alia, an (optionally substituted) phenyl radical, R.sup.2 represents, inter alia, an alkyl radical, and R.sup.3 represents, inter alia, a cycloalkyl radical, are obtained in very good yields and at high purity--i.e. free from the isomeric O-carbamoyloxytetrazoles (Ia)--by reacting tetrazolinones of the formula (II) with carbamoyl halides of the formula (III) (X=halogen) ##STR2## in the presence of an acid acceptor and in the presence of a diluent, at temperatures of between 0.degree. C. and 200.degree. C., and either isomerizing the O-carbamoylation product of the formula (Ia), which is formed under these circumstances as a byproduct, into the desired product of the formula (I) by heating, or else converting it by hydrolysis or alcoholysis into water-soluble, and thus readily separable, components (variable (a)). Three variants (b), (c) and (d) which are closely related to this process (a) are also described: Process variant (b) proceeds in analogy with (a) but via the (novel, isolated) metal salts (IIa) of the tetrazolinones (II). In variant (c), the isomer (Ia) is isomerized thermally, either in pure isolated form or mixed with (I), while, in variant (d), the (Ia) isomer is removed from (I)/(Ia) mixtures by means of hydrolysis or alcoholysis. The novel intermediates (Ia) and (IIa) also belong, as such, to the subject-matter of the invention.