Structural and transport properties of ceramic LaMnO_3+δ are investigated for δ = 0-0.154. According to x-ray diffraction measurements at room temperature the crystal structure of this compound varies from orthorhombic (Pbnm) for δ = 0 to rhombohedrally distorted cubic (Pm3m) for δ = 0.065-0.112 and to rhombohedral (R3̄c) crystal symmetry for δ = 0.125-0.154. These structural modifications are confirmed by the Raman micro-spectroscopy measurements. The resistivity displays in the range δ = 0-0.154 an activated behaviour both above and below the paramagnetic (PM) to ferromagnetic transition temperature, T _C. In the field of 8 T the relative magnetoresistance, Δρ(B)/ρ(0), reaches at δ = 0.154 the values of -88% near T_C and -98% at T ≈ 20 K. The resistivity of the PM phase of LaMnO_3+δ with δ = 0.100-0.154 satisfies the Shklovskii-Efros-like variable-range hopping (VRH) conductivity law between T_C ∼- 130-160 K and the VRH onset temperature T_v ∼- 250-270 K. The resistivity is governed by a complex energy dependence of the density of the localized states near the Fermi level, comprising a soft Coulomb gap A % 0.43-0.48 eV and a rigid gap γ ≈ 0.14-0.17 eV, the latter being connected to formation of small polarons.