Prepositional contexts in spanish and in german. a contrastive approach

German adpositions and Spanish prepositions are currently seen as rather similar units, except for some less important features, such as the order of some German adpositions and their greater richness in the expression of locative relations. However the grammatical behaviour of both units is actually quite different. This difference is the result of a more extensive use of prepositions as grammatical markers in Spanish, as well as the different tendencies of each language as for the way to express locative contents. This paper aims to highlight the contrast of German and Spanish in a very specific grammatical aspect of the unit: the ad/prepositional complements available in each case. A study of this contrast reveals deeper differences in the category of ad/preposition itself in each language.