Bulk superconductor samples of YBa2Cu3O7-δ (YBCO or Y-123), with additions of 0.15 wt% MoO3, TiO2, RuO2 and two different types of Al2O3 compounds, are synthesized by a solid state reaction route. Structural, magnetic and transport properties of the samples are characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), magnetic (M-H, M-T) and magneto-resistivity (MR-T) measurements. SEM investigations show that the addition of the Al2O3 obtained from the alumina crucible (Al2O3-cru) decreases the grain size of the sample which, in turn, degrades the transition temperatures (Tc) and magnetic critical current densities $$(J_{c}^{mag} )$$ . On the contrary, the addition of the other metal oxides enhances $$J_{c}^{mag}$$ of the samples by a few times and also increases Tc by up to 3 K. EDX analyses of the samples exhibit homogeneous distribution of additions, except for Ru-heterogeneities located around superconducting Y-123 grains. The highest Jc and Tc values obtained on the RuO2 added sample were attributed to the agglomeration of the Ru-particles, which led to the optimal porosity that supports oxygenation process and intergrain coupling of the structure. From the DC magnetization data, we estimated $$J_{c}^{mag}$$ of 3.1 × 105 A/cm2, 2.3 × 105 A/cm2, 2 × 105 A/cm2, 1.5 × 105 A/cm2, 105 A/cm2 and 5.1 × 104 A/cm2 for the RuO2, TiO2, MoO3, Al2O3, undoped and Al2O3-cru added samples at 5 K under 0.25 T, respectively.