Co-crystals may open the door to product tailoring of pharmaceutical products. Selected pharmaceutical ingredients were co-crystallized by mechanical and supercritical methods and the products were characterized by means of X-ray diffraction (XRD) using synchrotron radiation. The experiments revealed sub-micron and nano-structured composite particles, and three new phases, i.e., one cholesterol and two caffeine based. The phase separation and structure resolution of the new phases will form the aims of future investigations.