Glasses in the system $CaO-TiO_2-SiO_2-Al_2O_3-ZrO_2-B_2O_3$ were investigated to find the glass seal compositions suitable for use in the planar solid oxide fuel cell (SOFC). Glass-ceramics prepared from the glasses by one-stage heat treatment at $1,000^{circ}C$ showed various thermal expansion coefficients (i,e., $8.6 imes10^{-6^{circ}}C^{-1}$ to $42.7 imes10^{-6^{circ}}C^{-1}$ in the range 25-$1,000^{circ}C$) due to the viscoelastic response of glass phase. The average values of contact angles between the zirconia substrate and the glass particles heated at 1,000-$1,200^{circ}C$ were in the range of $131^{circ}pm4^{circ}$~$137^{circ}pm9^{circ}$, indicating that the glass-ceramic was in partial non-wetting condition with the zirconia substrate. With increasing heat treatment time of glass samples from 0.5 to 24 h at $1,100^{circ}C$, the DC electrical conductivity of the resultant glass-ceramics decreased from <TEX.$14 imes10^{-5}Omega^{-1} extrm{cm}^{-1}; to; 4.0 imes10^{-5}Omega^{-1} extrm{cm}^[-1}$</TEX> at $800^{circ}C$. Isothermal hold of the glass sample at $1100^{circ}C$ for 48h resulted in diffusion of Ca, Si, and Al ions from glass phase into the zirconia substrate through the glass/zirconia bonding interface. Glass phase and diffusion of the moving ion such as $Ca^{2+}$ in glass phase is responsible for the electrical conduction in the glass-ceramics.