In this article, the performance of the proposed magnetic horn to be used in the Neutrinos from Stored Muons, nuSTORM, facility is investigated. The meson production process is monitored using simulations. The target and horn geometry were created using pyg4ometry. A magnetic field region inversely proportional to the radius is defined in the horn. Using a FLUKA simulation, a 100 GeV proton beam impinges on the target inside the horn which then focuses and delivers the produced pions into the pion transfer line. Different horn currents were applied for delivering 2.64, 5 and 7.2 GeV/c pions. The phases spaces of the pion beam were plotted using ROOT. Setting the emittance to 0.2cm, the Twiss parameters are determined to be α = −0.42 ± 0.01, β = 410 ± 1 cm and γ = 0.00287 ± 0.00002 cm−1 such that the best acceptance can be achieved.