Experimental results of spherical glow discharge for a portable neutron source are presented. An experimental device consisting of a 45-cm-diam, 31-cm-high stainless steel cylindrical chamber was constructed in which a spherical mesh-type 30-cm-diam anode was installed. A spherical grid cathode made of 1.2-mm-diam stainless steel wire was made into a 7-cm-diam open spherical grid. The system was maintained at a constant pressure of 1 to 15 mTorr by feeding hydrogen or deuterium gas. The visible and ultraviolet emissions from the device were measured using the spectroscopic method. Strong emission lines of hydrogen were observed, and all hydrogen lines were broadened, remarkably, by Doppler and/or Stark effects. From these data, beam ion velocity, electron density and temperature of the core plasma were estimated. Using deuterium gas, a steady-state neutron production rate of 104 s-1 was observed at a discharge of 40 kV, 2 mA. In the low-current region of several milliamperes, the neutron production rate was proportional to the discharge current to the power from ~1.1 to 1.4. The beam-background reactions were dominant in the measured range of voltage and current.