In order to quantify the reproducibility of the flow method described here and compare it to that of batch synthesis, we focused on the property that showed greatest variability in syntheses: the BET surface area (see discussion below). The surface areas for the materials synthesized in flow are substantially more narrowly distributed than those from the syntheses in batch, as shown in Table . Standard deviations for the HTs synthesized was less than 6.05 m 2 g -1 , which shows good control of precipitation and aging for the flow method. Greatest variability in batch synthesis was observed for the HT aged at 65 °C, which ranged from 27 -110 m 2 g -1 in six replicates. In comparison, four replicates of flow syntheses of the same HT had surface areas between 139 and 148 m 2 g -1 . Similar trends were observed for the Fe HT and the Ni HT aged at 65 °C.