As a simple structured representative for the study of the adsorption dynamics of triazine containing polycyanurates the 2,4,6-triphenyl-1,3,5-triazine (TPT) adsorbed on Si(lll) has been investigated by scanning tunneling microscopy (STM). Even in the case of the TPT, an adsorption very similar to other more complex molecules of the same type is found : the non-dissociative adsorption is governed by a two-dimensional domain pattern formation. In addition it is found that the three phenyl groups and the central triazine ring of the investigated molecule lie in plane flat on the silicon surface. The STM images obtained after hearing the TPT-covered substrate to 900 K suggest that a mobile precursor precedes the final molecule surface bonding.