Dense BaTi_1-xHf_xO₃ (BTH) (x = 0.03; 0.05; 0.10; 0.20; 0.30) ceramics were obtained from powders prepared by the "acetate" variant of the sol-gel method and consolidated by alterative techniques, i.e. conventional sintering (CS) at 1400^oC/4 hours and spark plasma sintering (SPS) at 1200^oC/2 min, respectively. All the BTH ceramics are single-phased, regardless of the sintering procedure. For the BTH-CS samples the increase of Hf content from x = 0.03 to       x = 0.30 induces the decrease of the average grain size from 233.1 mm to 8.33 mm, while for the BTH-SPS specimens the same trend was observed, i.e. the values of the average grain size decreases from 25.3 mm to 0.97 mm. Relative density values ranged between 92.2 - 96.5% and 95.4 - 99.1% were obtained for the BTH-CS and BTH-SPS samples, respectively. Electrical measurements performed in the temperature range of (-250 - 200^oC) indicate the effect of hafnium addition in decreasing the ferroelectric-paraelectric phase transition temperature, irrespective of the consolidation technique. For the BTH-CS ceramics with lower Hf content (x < 0.10), very sharp permittivitty maxima, indicating a typical ferroelectric behaviour, were recorded. The presence of an increasingly higher proportion of Hf solute induces the shift of the lower-temperature phase transitions, i.e. tetragonal-orthorhombic and orthorhombic-rhombohedral towards higher temperature values, so that a single "pinched" ferroelectric-paraelectric phase transition was found for BHT-CS ceramics with x > 0.20. In this case, the increase of the diffuseness of the permittivity maximum shows a second order phase transition, specific to a ferroelectric-relaxor crossover. Concerning the BTH-SPS ceramics, excepting the sample with the lowest Hf content, the other ceramics exhibit (at 1 kHz frequency) higher relative permittivity values over all the investigated temperature range, than those recorded for the conventionally sintered specimens of similar composition. For the specimens with lower Hf content (x < 0.05), even if all the three phase transitions are still detectable, they are much more flattened relative to the samples consolidated by conventional sintering. Irrespective of the consolidation technique used, the highest values of the permittivity maximum was recorded for the ceramic samples with a Hf content corresponding to the substitution degree x = 0.20. Higher values by about an order of magnitude of the dielectric losses (tan d ~ 10^-1) were recorded for the BTH-SPS specimens, in comparison with those (tan d ~ 10^-2) determined for the BTH-CS ceramics.