Arrays of copper(I) sulfide (Cu2S) nanowires, with different morphologies, are prepared by the solid–gas reaction between Cu foil and a mixture of H2S and O2. Characterization of the Cu2S nanowires is performed by scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, and diffuse reflectance spectroscopy. Results show that Cu2S nanowires exhibit a Cu2S/CuxO (x = 1, 2) core/shell structure. The morphology and light absorption properties of the nanowires are shown to be dependent on the composition of the reagent gases, H2S and O2. When the H2S:O2 ratio is decreased from 1:0.5 to 1:0.8, the average diameter and length of the nanowires change from 270 nm to 3.1 μm to 114 nm and 8 um, respectively. A morphological change from columnar-like to wire-like structures is observed. When the H2S:O2 ratio is further decreased from 1:0.8 to 1:1, nanowires exhibit an average diameter and length of 670 nm and 3.7 um, respectively. A morphological change from wire-like to nail-like structures is also observed. Cu2S nanowire arrays presented strong enhanced light absorption properties, with a lowest recorded average light absorption value of 79%. Light absorption properties of Cu2S nanowire arrays are also determined by controlling the H2S:O2 reagent gas composition ratio. Results demonstrate good potential for the use of Cu2S nanowire arrays in solar energy applications.