MoO3 intercalation compounds with nicotinamide (nic) and hexamethylenetetramine (hmta) were synthesized at room temperature, by suspending alpha-MoO3 in a water-ethanol solution of nic or hmta. Six intercalation compounds of the formula MoO3.(nic)(0.20), MoO3.(nic)(0.40), MoO3.(nic)(0.56), MoO3.(hmta)(0.4), MoO3.(hmta)(0.60) and MoO3.(hmta)(1.12), named as Mo1, Mo2, Mo3, Mo4, Mo5 and Mo6, respectively, were prepared. The obtained hybrid matrices were characterized by elemental analysis, infrared spectroscopy, thermogravimetry, X-ray diffractometry and scanning electron microscopy. The obtained X-ray data, as well as molecular lengths of nic and hmta calculated by using Spartan-Pro 1.0.3 package shows that the total amount of intercalated nic molecules, as well as the orientation of the organic specie into the inorganic interlayer space (interaction with the acidic Lewis sites on the surface) is dependent on the organic moiety/oxide ratio. Comparing nic with hmta results, can be verified that MoO3 exhibits a higher affinity towards nic than hmta, since for nic an increase of the organic moiety/inorganic substrate ratio increases the total amount of intercalated molecules, whereas for hmta an opposite behavior is observed, with substitution of hmta by water molecules into the interlayer space. (C) 2004 Published by Elsevier B.V.