Antimony (Sb) is a metalloid whose increased presence in atmospheric particulate matter is of concern since its effects on living beings are unknown. The present study aims to characterise the redox chemical changes of SbV in vitro using a murine macrophage cell line, RAW 264.7. Analysis of the redox chemical changes revealed that SbV is partially reduced to SbIII when in culture. SbV induces the formation of reactive oxygen species, which may be causally related to the reduction of this chemical species. The expression of pro-inflammatory genes, which includes TNF-α and COX-2, was upregulated in response to SbV. The secretion of TNF-α protein was significantly higher from cells treated with SbV than the untreated controls. The pro-inflammatory response to SbV was determined to be dose-dependent. The signalling pathway underlying the cellular response to SbV is likely to be independent from the TLR4-mediated mechanism of lipopolysaccharide activation. This is the first study to describe the potentially pro-inflammatory effects of SbV on mammalian cells.