He was the 2014 recipient of the Sense about Science/Nature Maddox Prize for "Standing up for Science in the face of Adversity", and is a fellow with the Committee for Skeptical Inquiry.

[5] Grimes did doctoral work on ultraviolet radiation physics at Dublin City University funded by an Irish Research Council award,[6] under Neil O'Hare and Greg Hughes, and graduated with a Ph.D. in 2011.

[8][additional citation(s) needed] Grimes is best known for science journalism and outreach, and has contributed to numerous publications, including Irish Times,[24] The Guardian,[25] the BBC, and other outlets.

He has particularly criticised dubious claims linking cannabis to cures for cancer and autism,[37] saying that these positions are not supported by the evidence and could put patients at risk.

[43] Grimes has written at length about questionable treatments for conditions such as electromagnetic hypersensitivity which, evidence suggests, is a psychological rather than physiological illness, criticising clinics who claim to offer cures for the ailment.

[46][47] Grimes states that a major challenge in communicating about science is not strictly information deficit but rather ideological bias, and that motivated reasoning is a vital factor to acknowledge.

[48] Similarly, he has argued, both in popular media and academically, that acceptance of nuclear power, gun control and vaccination is strongly influenced by ideological beliefs.

[49][50] Grimes argues that overcoming our implicit biases and gaining a better understanding of the scientific method would improve our decision making and benefit both society and individuals.