X-ray single crystal diffraction technique has developed very rapidly for low molecular weight compounds to protein and metalloenzyme crystals. The development in both the instrumental and softwares are often the starting point for mechanistic and computational studies and inspire synthetic modelling chemistry. However, the number of crystallographer in the country is very limited although the need for the x-ray structural information has increased as more chemists involve in the synthesis of new compounds and structural studies. In the present seminar, the structure of three compounds namely (i) Bisiron(III) trifluoroborate, an unexpected product from the reaction of bis(2-pyridylketone) and FeBF4, (ii) 8H-Benzo-1,3benzodioxolo<6,5,4-de>quinolin-8-one(Oxocrebanine), (iii) an believable product from natural product research will be discussed to demonstrate the contribution of the technique. The first example lead to the discovery of new mechanism.