Anodizing aluminum in a pyrophosphoric acid solution (H4P2O7) causes the formation of numerous anodic alumina nanofibers. The nanofiber-covered aluminum surface exhibits superhydrophilicity measuring less than 10° in water contact angle (WCA). In contract, as the alumina surface is modified with a self-assembled monolayer (SAM), the WCA value changes to show superhydrophobicity measuring more than 150°. In the present investigation, the fabrication of highly sticky and slippery aluminum alloys was achieved by optimizing the nanostructure of anodic alumina nanofibers formed on the surface. Commercially available 3004 aluminum alloys (composition: 1.0-1.5 wt% Mn, 0.8-1.3 wt% Mg, small amounts of Cu, Zn, Fe, and Si) were chemically polished in a 2.5 M NaOH solution at 333 K for 5 min, and then were immersed in a 4.0 M HNO3 solution at room temperature for 30 s. The polished specimens were immersed in a pyrophosphoric acid solution (74.0 wt%) at 293 K, and then were anodized at a constant voltage of 75 V for up to 60 min. After anodizing, the specimens were immersed in a 1.5 mM 3,3,4,4,5,5,6,6,7,7,8,8,8,-tridecafluorooctylphosphonic acid (FOPA)/ethanol solution at 313 K for 48 h. The slipping behavior of the water droplet formed on the anodized specimens was examined by advancing and receding contact angle measurements using an optical contact angle meter. As the aluminum alloys were anodized in a pyrophosphoric acid solution, numerous anodic alumina nanofibers with the insoluble intermetallic compounds were formed on the surface. The length of the nanofibers increased with the anodizing time, and many nanofiber-tangled intermetallic particles were exposed to the surface. Figure 1 shows the changes in the advancing contact angle, θ adv, and the receding contact angle, θ rec, on the SAM-modified aluminum surface with anodizing time, t a. The θ adv value increased to approximately 170° by pyrophosphoric acid anodizing, and this superhydrophobicity was maintained upon further anodizing up to 60 min. On the other hand, the θ rec value drastically changed with anodizing time. As a result, the contact angle hysteresis (θ adv - θ rec) was also changed with anodizing time. Therefore, the adhesion interaction between the water droplet and the aluminum surface can easily be controlled by pyrophosphoric acid anodizing. Figure 1