All-solid-state sodium cells (Na15Sn4/Na3PS4 glass-ceramic/a-TiS3) showed a high capacity of over 300 mAh per gram of TiS3 at the 1st discharge–charge cycle. The capacity was gradually decreased to 100 mAh g−1 at the 10th cycle. Nyquist plots of the cell showed that the resistance of the a-TiS3 composite electrode became larger with the discharge–charge cycles. The XRD patterns of the a-TiS3 composite electrode before and after the 1st cycle indicated that the a-TiS3 was still amorphous during discharge–charge process. The Raman bands attributable to a-TiS3 were also observed after the 1st cycle. The SEM images and EDX mapping indicated that the a-TiS3 particles aggregated in the electrode after the 10th cycle. The all-solid-state sodium cell using a-TiS3 composite electrode with acetylene black as a conductive additive showed the high capacity of over 300 mAh g−1 for 5 cycles.