Morello is famed for his guitar style, which consists of blues, heavy metal, and punk hybrid riffs and funk/hip hop-inspired sounds. His guitar playing is also characterized by heavy use of guitar effects, such as delay, modulation, wah, harmonizers, distortion, feedback, and others in unique ways and combinations. The most recognizable effect in Morello's arsenal is the Digitech Whammy, which helps him create many of his sounds.
Critically acclaimed, he is said to use the guitar in a unique and imaginative way; rather than just plucking the strings, his maneuvers include toggling between two pickups - one on and one off - while rubbing his hands on the strings over the pickups; uses the bridge pick up (his signature vinyl scratch effect used in "Bulls on Parade"). He also uses techniques such as rapidly hitting a pencil on the strings ("Cochise", although he now emulates the sound by "baby-tapping" the strings), scraping an allen wrench on the strings for a whole song ("People of the Sun") and even tapping or scratching his pick-ups and strings with his audio jack cable.
To assist in his alien guitar sounds, Morello chooses various effects pedals. During his tenure in RATM, he used a Dunlop Cry Baby, a Digitech WH-1 Whammy, a Boss DD-2 Digital Delay, a DOD EQ pedal (used to boost the volume during guitar solos), and an Ibanez DFL Flanger. Around the time of The Battle of Los Angeles he added a Boss TR-2 Tremolo pedal (which can be heard on "Guerrilla Radio"). For Audioslave, Morello replaced the Ibanez Flanger with a MXR Phase 90. His amplifier of choice has always been a 50-watt Marshall JCM 800 2205 and a Peavey 4x12 cabinet. Though the Marshall is his amp of choice with Rage Against the Machine, he used a Vox AC30 combo amplifier to record multiple tracks on Audioslave's 'Revelations' album. While the Marshall amplifier has two channels, he only uses the overdrive channel, and simply turns down the volume on his guitar to get cleaner sounds.
In the studio, Tom uses the same setup for the bulk of the guitar tracks. For The Battle of Los Angeles, he also used a few other amps, such as a Line 6 as heard on the clean, spacey intro of "Mic Check," plus a Pignose mini-amp and a MusicMan "Twin" style amp. Morello has used several guitars throughout his career, two of the most well-known being branded "Arm the Homeless" and "Soul Power", with "Arm the Homeless" available to play in Guitar Hero I: Legends of Rock. He also uses an acoustic guitar called "Whatever It Takes" for his performances under the alias The Nightwatchman.