Fe-doped ZnO (FZOs) nanostructures with different doping concentrations (0;1;3;5;7 and 9 %.wt), were prepared via the dip coating technique. The effects of Fe doping concentration on the structural, morphological, optical, electrical properties and response to isobutane (i-C4H10) gas of FZO nanostructures were investigated. The XRD analysis showed that Iron has a significant effect on the particle size. SEM images revealed the formation of nanoparticles and nanotiges, EDS results confirmed the presence of Zn, O and Fe elements. AFM revealed that all samples have a homogeneous granular structure with nanometric dimensions. UV-Vis absorption measurements showed a transmittance between 69 and 89%, and optical gap decreases with increasing Fe. Electrical Hall effect measurements showed that the electrical properties of FZOs nanostructures have n-type conduction.Isobutane detection results clearly showed that the 3%.wt Fe-doped ZnO nanostructure offered a remarkable response of about 76.3% with a fast response time of about 67 s.