Background: Antacids are frequently used as over-the-counter (OTC) medications to reduce symptoms of dyspepsia and to neutralize stomach acidity. Evaluation of antacids efficacy depends on in vitro testing like acid neutralizing capacity (ANC) and acid neutralization potential (ANP). The purpose of this study was to examine ANC, ANP, and other characteristics of commercially available antacid formulations (both liquid and solid formulations) in the Gaza Strip. Methods: Both liquid (n=2) and solid (n=4) antacid formulations were acquired from the Gaza Strip’s central community pharmacies. Preliminary antacid test (PAT) was carried out to determine if the tested formulation is classified as antacid. The general monograph <301> in USP34/NF29 was used for the estimation of ANC, while ANP was investigated using Rossett Rice procedure. Both tests were conducted to evaluate the efficacy of antacid. In addition, cost effectiveness per formulation and statistical analysis test of data were calculated. Results: All formulations were classified as antacids because they all passed the PAT test (pH of antacid-HCl over 3.5). The ANC of antacids (n=6) varied from 8.74±0.37 to 29.14±0.84 mEq per minimum labeled dose (MLD). The ANC/MLD ratios for solid formulations were higher than those of liquid formulations. No statistically significant difference in ANC/MLD between the two groups was estimated (P˃.0.05). ANP test - the time duration during which an antacid formulation maintains pH above 3.5 - ranged from 43 to 90 minutes. According to this study liquids were inefficient in acid neutralization and expensive as a result. Conclusions: The ANC and ANP results indicated the better neutralizing efficacy and duration of solid antacids in comparison to liquids. A1 and A2 formulations– calcium and magnesium salt based solid antacids had the most appropriate properties in terms of efficacy, onset and duration of neutralizing activity. Antacids in the form of chewable tablets were the most cost-effective formulations. It is recommended to examine more batches of the same antacids and to add ANC data on the label of antacids.