When Bi2O3-containing glasses are melted at relatively high melting temperatures, they often show brown coloration due to the reduced Bi species, which is undesirable as optical glasses. In the present study, the low melting temperature (900 degrees C) compared with conventional ones (1000 degrees-1200 degrees C) was used, in order to avoid the formation of reduced Bi species. ZnO-Bi2O3-B2O3 (ZBiB) glasses were selected for developing molding glasses with low T-g (<= 600 degrees C) and high n(d) (>= 1.8). Most ZBiB glasses containing both B2O3 >= 40 mol% and Bi2O3 <= 40 mol% have much higher n(d) (= 1.87-2.10) than those of ZnO-Bi2O3-P2O5 glasses (n(d) = 1.68-1.97), much lower T-g (=400 degrees-470 degrees C) than those of Li2O-ZnO-TiO2-B2O3-P2O5 glasses (T-g = 550 degrees-570 degrees C), and much lower lambda(70%) (= 39-45) than those of commercially available molding glasses (lambda(70%) = 44-50) with n(d) >= 1.85. Some of the ZBiB glasses have properties suitable for precision glass molding (T-g = 466 degrees C, n(d) = 1.929, lambda(70%) = 41 for 10ZnO center dot 30Bi(2)O(3)center dot 60B(2)O(3) glass; T-g = 440 degrees C, n(d) = 1.946, lambda(70%) = 42 for 40ZnO center dot 20Bi(2)O(3). 40B(2)O(3) glass). Thus, ZBiB glasses containing both B2O3 >= 40 mol% and Bi2O3 <= 40 mol% melted at 900 degrees C are considered to be promising materials as molding glasses with high n(d) and low lambda 70%.