Objective To investigate the changes in the water loss rate and palatability of cockroach-killing gel baits at different time after application. Methods Three commercially available common gel baits were selected: gel bait P (effective constituent: 2.15% imidacloprid), gel bait W (0.5% dinotefuran), and gel bait S (0.5% dinotefuran). Water loss rate was determined by weighing the gel baits over a period of 20 days. The palatability of gel baits to Blattella germanica was determined by observing the feeding behavior of cockroaches during the same period. The analysis of variance and non-parametric test were used to compare the water loss rate and palatability of the gel baits. Results The three gel baits were dotted indoors for 20 days. Water volatilization mainly occurred in the first day, and the water loss rate was (39.73±0.05)% for gel bait P, (32.49±0.04)% for gel bait W, and (22.99±0.16)% for gel bait S, with a statistical difference between the baits (F=179.966,P=0.005). The weight of the gel baits was generally unchanged during the following 20 days. Under the fresh condition, the feeding frequency and total feeding time of the three gel baits were in the order of P>W>S. The feeding frequency and total feeding time decreased over time for all the three baits. After 7 days, there were no statistical differences in feeding frequency and total feeding time between gel bait P [(14.33±3.54]times and (518.00±237.91) s, respectively) and gel bait W [(15.67±4.85)] times and (414.00±263.92) s, respectively) (F=0.246, P=0.631; F=0.428, P=0.528); both gel baits P and W showed statistically higher feeding frequencies and statistically longer total feeding time compared with gel bait S [(4.33±2.21)] times and (38.50±19.75) s, respectively) (F=14.038, P=0.002, P=0.001; F=7.536, P=0.007, P=0.034). After 14 days, gel bait P had better palatability than gel baits W and S. Conclusion The water loss of the gel baits mainly occurs in the first day after placement. The gel baits have the best palatability in the fresh state, and show different degrees of decreases in palatability with time. In general, gel baits P and W have the best palatability within 7 days. It was not found for the correlation between water loss rate and palatability for the three gel baits.