mina, polycarbonate membranes, block copolymers etc. have opened up the possibilities of the synthesis of arrays of ordered nanowires of a number of materials. Use of electrodeposition to synthesize ordered arrays of nanowires in such templates is well studied. However till date there are very few reports of the synthesis of arrays of metal nanotubes [8–15] using nanoporous templates. Most of the earlier work in this area involve chemical modification of the pore surface of porous templates to enhance the deposition of the metal on the pore walls. Such chemical modifications often add impurities to the nanotubes. [12,13] These methods are often specific for a particular kind of metal to be deposited and cannot be used for a variety of materials. Often it is also specific to an application. The processes are time consuming because of the complexities involved. [12,13] Thus a general and efficient method for the synthesis of metal nanotubes (with controlled length, diameter and wall thickness) still remains a challenge particularly in templates which allow synthesis of large ordered arrays. We present here a novel, versatile and general approach for preparing metal nanotube (MNT) arrays. The method uses a template like anodic alumina and has full control on length, diameter and wall thickness of the nanotube. The method is general enough and in principle, can be applied to prepare single metal nanotubes of all metals which can be deposited by electrodeposition technique. This method in principle can also be used to deposit nanotubes of many semiconductors which can be prepared by electrodeposition. The method of synthesis of metal nanotube arrays described here exploits the basic principle of electrodeposition in a rotating electric field, which we believe has never been utilized in such synthesis using electrodeposition. The novelty of this method lies in its generality, simplicity and efficiency. As a generic example, we report the synthesis of single crystalline copper nanotube arrays by electrodepositing copper into the pores of porous anodic alumina template in the presence of a lateral rotating electric field which is applied in addition to the longitudinal d.c electrodeposition current. The applied rotating field as our simulation shows (described later on) makes the ions graze the surface of the pores in helical paths and thus makes the deposition selectively occuring in the region near the wall of the nanopores. The single crystalline copper nanotube arrays are prepared by electrodeposition in nanoporous anodic alumina membranes placed in the plane of a rotating electric field. Two sinusoidal electric fields of the same amplitude with a phase difference of p/2 (as shown in Scheme 1a) constitute the rotating electric field. The principle is well illustrated in Scheme 1. With average direct current densities (Faradic current that does the actual deposition) of 6 mA cm –2 , the time of deposition of the tubes in 200 nm pore diameter anodic alumina membranes (membrane area = 1 cm 2 , membrane thickness = 60 lm) is 15–20 min. This shows that the method is relatively faster than other reported methods. [12,13]