The gas of the Seyfert 2 galaxy NGC 5252 consists of an ionized bicone of gas and a region of neutral gas which fills the regions outside the ionized bicone. We present new HI maps of the neutral components with a spatial resolution which exceeds previously available maps by a factor of 2. In addition, the ionized component was imaged in the Hα 6563-A emission line. A comparison of the physical properties of both extended gas systems leads to the following results. (1) HI column densities range from 2 to 5x10^20 cm^-2, in fair agreement with those found in the HII gas. (2) The two components of the gas follow a similar rotation pattern with comparable velocity amplitudes of about 100 km s^-1. At the central region, both the ionized and neutral gas are counter-rotating with a peak amplitude of about 150 km s^-1. These similarities of the two components of the gas suggest a physical connection between them. The most plausible configuration is a series of ring structures surrounding the optical body of the galaxy. A previous suggestion of a polar ring can virtually be ruled out by the new data. The complexity of the gas system suggests an external origin for the gas in NGC 5252 such as a merger with a gas-rich system. Finally, a search for molecular material in the nuclear region of the galaxy led to an upper limit on the central H_2 mass content of 2x10^8 h^-2 M_solar within the central 4h^-1 kpc (11 arcsec). The low molecular content is consistent with an unusually high nuclear extinction if the material is highly concentrated in the central region.