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The mechanisms leading to a maximum of j/sub c/ as a function of reaction time in (Bi,Pb)/sub 2/Sr/sub 2/Ca/sub 2/Cu/sub 3/O/sub x/ monofilamentary tapes are investigated. Various properties of tapes previously reacted 40 hours in air at 837/spl deg/C, rolled, and submitted to additional reaction during times varying from 40 to 240 hours were measured. The evolution of morphology, phase assembly, stoichiometry, weight, critical temperature, critical current and irreversibility line is described. XRD and SEM analysis reveal no decomposition of the Bi(2223) phase and no noticeable grain growth in the time window under investigation. Pb losses as function of reaction time up to 40% were detected by means of thermogravimetry and EDX, while an increase of T/sub c/ from 107.25 to 109.1 K was observed. Transport and magnetic measurements show that the observed maximum of j/sub c/ at about 180 hours is the result of two competing effects: a) an improvement of the quality of grain boundaries and b) a decrease of the pinning efficiency in the grains.