Improving operational performances of working dog–human dyads is receiving more and more attention. Despite this interest, the associations between human personality, dog personality, dog-human personality matching and dyad performances have rarely been addressed. This study explores the links between human and dog personality traits, their matching, the human-dog relationship, and dyad performances of handlers and working dogs belonging to the canine unit of the Paris Firefighters Brigade. Using a repeated searching task in a training field, we evaluated the performances of 14 dyads using three parameters: searching speed, searching precision and speed improvement of the dyad. Using a questionnaire, we assessed the quality of life of dogs (activities, relationship between handlers and their dog). Personality traits (neuroticism, extraversion, openness to experience, agreeableness, conscientiousness) and subtraits of handlers (30 subtraits belonging to the five human traits) were determined using the NEO-PI-R questionnaire, and personality traits of the dogs were investigated through six subtests that allowed us to characterize five dog personality traits. We compared the performances of dyads in relation to the human-dog relationship and correlated these with human, dog personality traits and their matching. Dyad performances were different depending on the quality of life of the dog and the human-dog relationship: dogs with toys at home showed a lower improvement capacity, while dogs with few physical punishments showed a lower number of errors in the searching task. The dog personality trait “human familiarity” was correlated with dyad performances, with a higher improvement (r=0.52, p=0.05) but a lower performance speed (correlation with total time of the searching task: r=0.55, p=0.05). Human “deliberation” (i.e. “conscientiousness”), “aesthetics” (i.e. “openness”) and “modesty” (i.e. “agreeableness”) were all positively related with precision of the searching task (correlation with the number of errors: r=−0.48, p=0.08; r=−0.52, p=0.05; r=−0.51, p=0.07). Human “dutifulness” (i.e. “conscientiousness”) and “activity” (i.e. extraversion”) were positively related with dyad improvement (r=0.61, p=0.02; r=0.52, p=0.06; respectively) while human “excitement seeking” was negatively related to dyad improvement (r=−0.50, p=0.07). Dyads with handlers higher on “gregariousness” (i.e. “extraversion”) were more efficient when speed was considered (r=−0.60, p=0.023).Matching dogs and humans on “neuroticism” traits (human “anxiety” and dog “neuroticism”) was negatively correlated with improvement (r=−0.52, p=0.06). Matching of dog “activity-exploration” and human related subtraits to “extraversion” (“activity”, “positive emotions”) was correlated with higher speed (human “activity” and dog “activity-exploration” r=−0.50, p=0.07 for time searching) but a lower precision (human “activity” and dog “activity-exploration” r=0.45, p=0.11 for number of errors) and a lower improvement (human “positive emotions” and dog “activity-exploration” r=−0.47, p=0.09). However, matching on human subtraits “positive emotions” and “activity” and the dog trait “human familiarity” was positively correlated with speed (r=−0.53, p=0.05 with time), precision (r=−0.55, p=0.04) and improvement performance (r=0.62, p=0.02). This preliminary study provides new hypotheses for future examination of factors associated with the performances of working dogs and their handlers that could lead to selection of more efficient dyads.