A simple synthesis of ribothymidine 3'-phosphate from uridine 3'-phosphate was described. Crystalline 5'-O-trityl- or 5'-O-monomethoxytrityl-derivatives of ribonucleotides are easily prepared and purified in relatively large batches through choices of appropriate solvents. Acylimidazoles together with a strong nitrogeneous base have been successfully used for the acylation of the hydroxyl and amino groups of the nucleoside and nucleotide, and the reaction mechanism was studied. The relative stability of different blocking groups of guanosine 3'-phosphate was compared. Oligoribonucleotide fragments including an octaribonucleotide of the T psi C- and D-loop of yeast alanine tRNA were synthesized. Quantitative analyses of the common ribo-nucleosides and -nucleotides were done by a modified RPC method.