Zn1-xCoxO (0 <= x <= 0.06) nanorods were fabricated by hydrothermal method. The effect of Co doping on the morphology, crystalline structure, optical and magnetic properties of the samples was investigated. The length of obtained ZnO nanorods increases with the increasing Co concentration. Based on the results of X-ray diffraction and Raman spectra, it is confirmed that a small amount of Co ions are incorporated into ZnO lattice. The segregated phase of Co3O4 was detected at x > 0.01. The absorption and photoluminescence spectra reveal the d-d electronic transitions of tetrahedrally coordinated Co2+ in ZnO host. Co doping induces fluorescent quenching of the visible emission bands related to surface states and defect states in the Co-doped ZnO nanorods. Weak room temperature ferromagnetism was observed in the samples with x = 0.01 and then paramagnetic characteristics of the samples with x > 0.01.