Las cepas de Clostridium, productoras de solventes y ácidos, han sido caracterizados empleando una amplia gama de técnicas fisiológicas, bioquímicas y moleculares. Los trabajos más recientes han clasificado estos microorganismos en cuatro grupos y es de esperarse que muchos de los microorganismos anaerobios solventogénicos estén fuera de esta clasificación. El presente trabajo estuvo orientado a caracterizar molecularmente por 16S rARN trece cepas silvestres de Clostridium seleccionadas por su mayor capacidad para producir solventes con respecto a la cepa patrón de Clostridium acetobutylicum ATCC824. Se hizo la secuenciación parcial del gen 16S rARN, sobre su segmento final (aproximadamente 700 pb). Para anali-zar las secuencias, se calculó p y se construyó el dendograma empleando neighborjoining. Se pudo obser-var que las cepas silvestres no pertenecen a ninguno de los cuatro grupos de Clostridium solventogénicos sino que están cercanamente relacionadas con Clostridium butyricum.Solventogenic and acidogenic Clostridium has been characterized by biochemical, physiological and molecular techniques. These microorganisms have been classified into four groups but these may not necessarily be the only four exclusive groups; in fact, many of these microorganisms might not belong to any of these selected groups. The main goal was to classify 13 higher solvent- producing Clostridia strains through molecular biology techniques; strains were isolated by our Group. Sequence analysis was calculated by p and the dendogram was constructed by neighbor-joining. The results obtained strongly suggest the idea of a high similarity between the 13 native strains in the study and the fact that they had no relationship to any of the 4 groups established by Keis et al (1995). It was found that Clostridium butyricum strain is the most related specie to the thirteen Colombian strains