In this work, mesoporous silica (MSN) was synthesized and tested for ammonia adsorption. The synthesized MSN was characterized using the Fourier Transform Infrared (FTIR), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), and Brunauer–Emmett–Teller (BET). In the ammonia adsorption experimental, the mass of MSN was varied at 0.5, 1.0, 1.5, 2.0 and 2. 5 g. The data of ammonia uptake by MSN was plotted using Langmuir and Freundlich isotherms, while the kinetic adsorptions were determined using pseudo-first order and pseudo-second order kinetics. The results showed the MSN structural was hexagonal form and particle size of 70 to 150 nm. Characterization using FTIR shows the MSN contained various chemical functional groups. The adsorption of ammonia rest resulted with a high percentage of ammonia removal. At 0.5, 1.0, 1.5, 2.0, 2.5 and 3.0 g of MSN, the highest adsorption uptake at 5 minutes were 0.79, 0.42, 0.31, 0.21, 0.17 and 0.12 mg/g, respectively. The adsorption data were fitted to the isotherm and kinetic models to predict the mechanism and kinetic characteristics of the adsorption process. The Freundlich isotherm model shows the highest correlation with the Freunclidh (KF) and adsorption constant (n) of 6.78 and 0.39 mg/g, respectively. For the kinetic modeling, the data of ammonia adsorption process were well fitted to the pseudo-second order with coefficient determination (R2) value of 0.9992. These results indicated the potential for a new application of MSN as an effective adsorbent for ammonia removal and it can be applied in the water treatment processes.