The present invention describes methods for the production of oligonucleotides under conditions which exploit the desirable characteristics, such as the property of sustaining high degrees of substitution, of functionalized organic polymeric supports while avoiding the sluggish kinetics and low rates of conversion which normally plague syntheses involving such solid supports. By employing the methods and materials disclosed, functionalized support, substituted to a degree of about 250 .mu.mol/g, can be utilized at greater than 98% conversion levels for each sequential nucleotide coupling cycle, to provide unprecedented amounts of isolated oligonucleotide per gram of solid support.