Di(tert-butyl)[(pyren-1-yl)methoxy]silyl chloride reacts selectively with the 5 '-hydroxy groups in deoxynucleosides and this can be removed under conditions which do not affect other commonly used acid or base labile protecting groups, yet it, is stable to phosphorylation conditions. While incorporated terminally at 5 '-OH of the long sequence viz., 26-mer, this group is also helpful in subsequent purification by HPLC as well as PAGE. Fluorescence properties of these sequences were studied to find the suitability of the approach.