Rapid synthesis of sodium-substituted lanthanum manganite phases is reported by the solution combustion method using oxalyl dihydrazide (ODH), as fuel. As-synthesized compounds are amorphous in nature; crystallinity was observed on heating at 800 degrees C for 5 min. Structural parameters were determined by the Rietveld refinement method using powder X-ray diffraction data. Parent LaMnO3 compound crystallizes in the orthorhombic structure (space group Pbnm No. 62). Sodium-substituted compounds crystallize with rhombohedral symmetry (space group R-3c, No.167). On increasing the sodium content, unit cell volume decreases and Mn-O-Mn bond angle increases. The fourier transform infrared spectrum shows two absorption bands around 600 and 400 cm(-1) for the compositions x=0.0, 0.05, and 0.10. Mn3+/Mn4+ ratio was determined by iodometric titration. Electrical resistivity measurements reveal a composition-controlled metal to insulator transition (TM-I), the maximum TM-I was observed for the composition La0.85Na0.15MnO3 at 285 K. Increase in magnetic moment is observed with increase in crystallite size. Room temperature vibrating sample magnetometer data indicate that for the composition up to x=0.10, the compounds are paramagnetic whereas composition with x=0.15, 0.20, and 0.25 show magnetic moments 34, 39, and 33 emu/g, respectively.