A convenient method for the synthesis of a new series of polyarylketones with relatively high molecular weights has been investigated. The polymers were prepared readily by direct polycondensation of terephthalic acid with a series of diaryl compounds using phosphorous pentoxide/trifluoromethanesulfonic acid (w/w = 1/10), phosphorous pentoxide/methanesulfonic acid (w/w = 1/10), and aluminum chloride/phosphorous oxychloride (w/v = 1/3) as condensing agents. Among the three, the phosphorous pentoxide/trifluoromethanesulfonic acid pair was found to be most efficient and was studied in detail. The thermal and crystalline properties of the resulting polyarylketones were characterized. All of the polyketones prepared in the present study are crystalline and their glass transition temperatures and melting points depend greatly on the structure of the diaryl compounds employed.