A twin gap magnetorheometer-based on a modified Anton Paar magnetocell MRD180/1T-using plate-plate gaps on both sides of the rotor plate, all plates consisting of ferromagnetic steel, is presented and compared to corresponding single plate-plate magnetorheometry. The twin gap arrangement uses a nonmagnetic housing at the rim, thus allowing nominal shear rates up to 10 000 s(-1) without sample loss due to centrifugal forces. Shear stresses in a range of 0.001-105 kPa are accessible. Finite element modeling (FEM) using MAXWELL (R) 2D verified the homogeneity of the flux density field in both shear gaps. The magnetic flux density in the magnetorheological fluid reaches up to 1.5 T and is obtained from an online Hall probe signal using a calibration factor from FEM. The radially constant flux density prevents radial carbonyl iron powder migration. Normal forces acting on both sides of the rotor compensate each other. Gap opening due to large normal forces as observed for the single gap geometry-requiring additional corrections for the effective flux density and shear stress-is not relevant. The apparent shear stress versus flux density characteristics from the twin gap and single gap magnetorheometry agree over the full range investigated (0-1.1 T), as shown for samples containing 90 and 85 wt % iron. Flow curves measured in a range of 0.016-3000 s(-1) are presented as true shear stresses versus shear rate. The twin gap design (patent pending) has been licensed to the magnetocell manufacturer.