Bi-0.5(Na1-xKx)(0.5)TiO3 (BNKT) bulk ceramics with a preferred <100> orientation were prepared using the reactive templated grain-growth method with platelike Bi4Ti3O12 particles as templates for BNKT. The potassium concentration (x value) had a large effect on the degree of orientation, and highly oriented ceramics were obtained for the specimens with x = 0.10 and x = 0.15, whereas the specimen with x = 0.00 had a small degree of orientation. Increased potassium concentration from x = 0.00 to x = 0.15 decreased the grain-growth rate and changed the grain shape from irregular to cubic. These factors were responsible for the increased degree of orientation.