Lanthanum apatite is one of the most promising materials as an electrolyte for intermediate-temperature solid oxide fuel cells (IT-SOFCs) which operate close to 700°C. Here, we report the preparation and optimization of dense La 10 AlSi 5 O 26.5 tapes obtained by the combination of tape casting technology and reaction sintering. Homogeneous concentrated mixed suspensions of La 2 O 3 , Al 2 O 3 and SiO 2 were prepared in ethanol. The effect of the solid loading, the binder content, ultrasound and the initial particle size of the materials onto the characteristics of the tapes (cracking, composition, microstructure and electrical properties) has been studied. This study paves the way for further improvement in the processing of oxyapatite electrolyte for solid oxide fuel cells.