Magnetic and structural properties of RCo12-xTix with R=Y and Sm compounds have been investigated by using x-ray diffraction and magnetic measurements. It was found that all compounds investigated are almost of a single phase with the ThMn12-type structure. x-ray diffraction patterns of magnetically aligned powder samples indicate that the easy magnetization directions (EMD) at room temperature are in the basal plane for SmCo12-xTix compounds while for YCo12-xTix compounds the EMDs are along the c-axis. The lattice parameters increase monotonically with increasing Ti content for all the compounds investigated. The Curie temperature Tc decreases monotonically with increasing Ti content for both YCo12-xTix and SmCo12-xTix. The saturation magnetization Ms decreases with increasing Ti content for all the systems. The anisotropy field μ0Ha of YCo12-xTix compounds decreases monotonically with increasing Ti content, while the Ti content dependence of the anisotropy fields μ0Ha for SmCo12-xTix compounds exhibits a maximum at about x=1.74, which can be understood in terms of a two-sublattice model of anisotropy.