Olive (Olea europaea L.) pomace (OP) is a by-product of olive oil production rich in phenolic compounds (PC), known for their anti-inflammatory properties. Nitric oxide (NO) is a reactive nitrogen specie and also a molecule involved in inflammation processes. This work looked to evaluate the effect of the bioavailable PC (BFC) of OP on NO levels in microglial cells. BPC of OP were obtained through in vitro gastrointestinal digestion using fractionated OP (OPF, particles size < 2 mm) and micronized OP (OPM, particles size < 20 µm). BPC profile was obtained by HPLC and mass spectrometry. NO levels were quantified by spectrophotometry in microglia BV-2 cells treated with BPC from OPF and OPM (0.03-1.5 mg L-1) for 24 hours and then activated with lipopolysaccharide (LPS), a known inflammation inducer, for more 24 h. Total BPC were higher in OPM than those observed in the OPF (16.02 ± 0.35 vs. 10.65 ± 0.04 mg L-1). This occured probably due the increase in the surface área induced by micronization, which facilitated the access of digestive enzymes. The activation of BV-2 cells by LPS resulted in increased levels of NO when compared with control group (166.5±7.90 vs. 100±0.01 %) and only the highest concentration of OPF and OPM (1.5 mg mL-1) was able to attenuate the NO levels increase (127,6±10,49 and 125.7±15.07%, respectively). These results indicated that although OPM and OPF presented diffrent PC bioavailability, these diferences did not reflect in their capacity of removing NO levels generated by LPS in microglial cells. This can be due the distinct distribution of PC subclasses in OPM in comparison with OPF, which may directly affect their potential to reduce NO levels, since PC may act synergistically. We demonstrated that BPC of OP may be a promising adjunct in inflammation processes, regardless the particle size.